JULES-CESAR SAVIGNY. 569 



contrary, which were forced into combinations as artificial as 

 by any the most arbitrary methods. What, for example, but 

 adherence to an arbitrary rule could bring the Mactra and 

 the Nucula into close affinity, and fix in the same order the 

 Pectunculus and the Chama with the Solenes, the Tellina?, 

 and the Venusidae ; and the Arcae with the mussels and the 

 Aviculas ? It is time, says Deshayes, to renounce these 

 artificial arrangements founded on a single character, arbi- 

 trarily assumed and made to dominate over all others. To 

 be natural, a classification ought to take into consideration 

 the whole essentials of the organism in the definition and 

 circumscription of the principal groups. It is by acting on 

 this principle that the best zoologists have arrived nighest to 

 the purposed end of their ingenious labours. 



A review of these various systems will have satisfied you, 

 I think, that none of them are superior, or even equal, to 

 Cuvier's, — the source and parent of them all. The first out- 

 line of Cuvier's was published on the 10th of May, 1795; 

 the last finish was given to it in March, 1830, and the strong 

 impress of it on the progress of Conchology can never be 

 erased. He has lifted the subject above raillery and ridicule, 

 and placed, in its due rank, a large class of animals, than 

 which none other more deservedly claim the attentions of the 

 naturalist, the physiologist, and the geologist. 



Note to page 532. 



To understand the original points in this and subsequent classifications of 

 the Tunicata, it is necessary to keep in view that of Jules-Cesar Savigny, 

 founded on the most delicate and elaborate dissections. Hence I shall here 

 give a synopsis of it, with a few preliminary remarks. 



Dr. John Albert Schlosser was the first to describe a beautiful and com- 

 mon production on our shores, which Linnaeus named Alcyoniuni schlosseri. 

 It is a firm gelatinous crust growing on sea-weeds and, less frequently, on 

 stones ; the surface marked with numerous small pear-shaped bodies arranged 

 round a central dot, and thus simulating a star as this is figured in geographical 

 maps. Schlosser believed that all these bodies which entered into the com- 

 position of eaeli star were intimately united at their smaller end, and consti- 

 tuted a true animal " much more beautiful than any polype, but quite of a 

 different structure." In each pear-shaped body he detected, near the outer 

 extremity, a small circular hole, which contracts and opens frequently ; and 

 in their common centre another "opening of a circular, oval, or oblong h'gure, 

 forming a kind of rising rim like a cup, which, when the animal is alive and 

 at rest, contracts and expands itself to many different degrees, with greal 

 alertness and velocity, though sometimes it remains a great while expanded 

 or contracted." At neither of the apertures could he perceive any tentacula, 

 " hut by looking into them very narrowly, he saw something like very tender 

 little fibres moving at the bottom of their insides." He believed the smallei 

 aperture to be the mouth. Phil. Trans, an. I 7;").""), abridg. x. (170. 



Ellis also examined this production, lb' found thai nil the interstices 



