Puslapio vaizdai
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Milne-Edwards, in a work* inferior to none of the many excellent ones with which he has enriched zoology, has proposed a new tribe or order in the class constituted of some recently discovered genera, -named Clavelina and Perophora ;-because each species consists of several individuals that pullulate from a common creeping tubular root, by which they are associated together organically, and so intimately that there is even a circulation established between the different individuals of the same group. This section Milne-Edwards calls the social,-ASCIDIES SOCIALES,-and it has been admitted by Professor Forbes. I think that the claim to this distinction cannot be allowed. The character on which it is asserted is one of secondary importance, as seems to me proved by the fact that the gap which would separate them from the simple Ascidians is greatly narrower, and less evident, than that which would separate the social from the compound Ascidians. In habit and structure, the social do not differ in any way from the simple kinds, but the social do differ very much in both particulars from the compound kinds. Hence, I think that they ought to be reckoned merely as a family in the tribe of Ascidiadæ.

Professors Forbes and Goodsir have proposed (1841) the establishment of another tribe under the name of PELONIADÆ, with a better reason, for there is a difference in habit and economy which justifies the conclusion that would be drawn from the anatomical structure. The Peloniada are simple Tunicata, but they are free, and have a habit that might seduce us to look for their relations among the worm

* Observations sur les Ascidics composées des Côtes de la Manche. Paris, 1844. 4to.

"Whilst

like members of the radiated division of animals. in many of their characters they approach the true Ascidians, especially the unattached species of the genus Cynthia, in others they indicate a relationship with the cirrhograde Echinodermata. They present the remarkable positive anatomical character of a union of mantle with test; so that there can be little question of their right to be regarded as members of a distinct family of Tunicata."*

And now I bid you farewell. I have felt, as I proceeded, a growing conviction of my incompetency for the task I had too willingly undertaken; but as you have followed, with patient steps, the tedious way, so I may flatter myself you are now fitted to pursue the future course unassisted. The last two letters have wearied you, and yet there was a purpose in this strain upon your attention, for, when nicely examined, you will find that the tabular views of the systems I have given you, with more or less minuteness of detail, not only mark the successive stages in the history of our subject, but introduce you to its masters, and familiarize you with the names of the principal divisions of the Mollusca, and with their leading characters. This, I have thought, was to be best done by oft repetition under different phases; and without this familiar knowledge you cannot enter, with any pleasure, on the perusal and use of the books that must aid you onwards, and enable you to correct and supply what is here erroneous or amiss.

Be careful, in conclusion, to ride your hobby leisurely and at a pleasurable pace. It is neither for you nor me to devote our time to natural history:-it is to be your recreation. "Every man must and will have some relief from his more severe pursuits," is an axiom I borrow from a wise and good man; and you do well to seek that relief in a study that calls at one and the same time the head and heart into healthful exercise. There is enough in Conchology itself and its collateral bearings, to put the mental faculties on the stretch; and the objects on which you are to work, in their careful observation and research, cannot fail to give birth to emotions and affections and impressions of a good and cheerful kind. They are the creations of Omniscience; and there is no evil there;-nay, you may safely look upon the species your study brings under your notice as so many moral emblems to be unriddled by your skill.

"When I consider Thy heavens, the work of Thy fingers, the moon and the stars, which Thou hast ordained; What is

* Forbes and Hanley's Brit. Mollusca, i. 42.

man, that Thou art mindful of him? and the son of man, that Thou visitest him? For Thou hast made him a little lower than the angels, and hast crowned him with glory and honour. Thou madest him to have dominion over the works of Thy hands; Thou hast put all things under his feet: All sheep and oxen, yea, and the beasts of the field; The fowl of the air, and the fish of the sea, and whatsoever passeth through the paths of the seas. O Lord our Lord, how excellent is Thy name in all the earth!"

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Cirrhobranchiata, 545, 588.
Cirrhopods, 7.

Cladopoda, 566.
Clam, 30, 38, 136.

Clavagella, 268.

Clavelina, 146.
Clausilia, 485.
Cleidotherus, 467.
Cleodora, 247.
Cleodores, 115.
Cleodoridæ, 586.
Clio, 116, 246, 270.
borealis, 117.
Cliona celata, 84.
Clionidæ, 586.
Cochlearia, 46.

Cochleæ, 476.

Cockles, 37, 41, 97.
Cœlopnoa, 553.
Colours, 233-38.
Conchæ, 459, 601.

Conchifera, 7, 347, 533, 552, 599.
Conchophora, 565.

Cones, 127.

Conus chinensis, 38.

tulipa, 234.

Corbis, 277.
Corbulæ, 293.

Crab, Bernard, 434.

Cranchia bonellii, 235.
Craniadæ, 600.

Craniæ, 422.

Crenella discors, 135, 164.

marmorata, 164.

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Crenellæ, 142.

Cellulacea, 542.

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Crepidula adunca, 420.

porcellaria, 419.

Creseis, 117.

Cribella, 270.

Crow, 27.

Cryptella, 369.

armatum, 244.

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Cryptobranchia, 562.

Cryptodibranchiata, 540.
Ctenobranchia, 562.

Ctenobranchiata, 552, 587.
Cucullæa, 294.

Cuttle, monstrous, 13, 14.
Cuttle-fish, 236, 315.
Cuvieria, 271.
Cuvieridæ, 586.

Cyclas, 136, 406.

cornea, 197, 348.

Cycladæ, 601.

Cyclades, 349.

Cyclidium, 350.

Cyclobranches, 108.

Cyclobranchia, 563, 577.

Cyclobranchiata, 544, 552.
Cyclo-gangliata, 181.
Cyclostoma, 127.

flavum. 488.

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