^44 Zoological Collections, Iiivertebrata, 



mouth, a singular phenomenon which had also been observed by M. Cuvier ;* 

 ^nd they have assured themselves of the injurious influence which another 

 animal of the same order, the Hermella, exercises over the oysters of Cancale, 

 where they have already destroyed one of the richest beds. 



2. MoUusca, The authors treat also of the habits of different moUusca 

 t)f the French coast, and they have had opportunities of observing many 

 animals of this class, either imperfectly known or entirely new. Amongst 

 the former may be cited Calyptraa, Phasianetla, Pleurobranchus, OncJddium, 

 fmd I)entaUuia ; and oHhaldtter, Actceon, Dorimorphus, Tecfura, -dnd CribeUa. 

 According to the observations of these naturalists, the Aplysia viridis of 

 Montagu, of which Ocken has formed the genus AciaoHf is remarkable in 

 having the general form of the Aplysice, whilst it is, at the same time, 

 distinguished from them by one of the most important chai'acters of its 

 organization ; it does not possess true branchiae, the common integuments 

 appearing to be the only respiratory organ. The genus CribeUa of MM. 

 Audouin and Milne Edwards, is also very remarkable ; for, although the 

 gasteropodous molluscum, which bears this name, has the form of the Pleu- 

 robrancfms, and also resembles this genus in having, on the right and left, 

 a groove which separates the loot from the mantle, it does not possess any 

 trace of branchiie in this hollow ; respiration seems to be performed by 

 the skin of the mantle, which is wrinkled on each side, and perforated by 

 an infinite number of pores. The Dorimorphiis of these authors is less 

 removed from the types already known, and occupies the middle, so to speak, 

 between the Doris and the Pleurobranchus. Lastly, their genus Teclura is 

 interesting, from affording a proof, more indisputable, perhaps, than any 

 other, that the study of shells, separated from that of the animals which 

 construct them, may lead to most erroneous clussiiication. In fact, this 

 genus has been established to receive a little red limpet of our coasts, (^Patella 

 parva ?) the animal of which, instead of resembling that of our common 

 linipet, has, like the Pileopsis, an anterior cavity contcdiiing a branchia ; and, 

 what makes it still more remarkable, is, that the form of the shell is exactly 

 similar to that of the Paiclla; there is neither depression nor groove which 

 can, as in the Siphonaiia, afford a distinctive character. — Cuvier, Rapport. 



Distribufion of the Invertehrol Animals of the French coasi.-f — In con- 

 sidering the topographical distribution of the invertebral animals of the coast 

 of France, ]\IM. Audouin and Milne Edwards distinguish four principal 

 zones or regions, comprized between the limits of the highest and lowest 

 water, — regions which are in general very distinctly marked, and which are 

 characterized by the species whose habitation is fixed within them. 



In the highest of these zones, which is always dry during common tides, 

 the Balani are found attached to the rocks ; few or no marine animals 

 frequent this region. 



The second zone commences a little below the level of the sea during 

 dead water. Where rocks occur, they are usually found covered with sea- 

 weed, and form the seat of the Turbo, Patella, Purpura, Natica, the red 

 Actinia, &c. ; on the fine sandy beach, we may hope to meet with the 



* In the Terebella coTichilegay belonging to a neighbouring genus, these tentarula are 

 employed in the construction of the tube, which is composod of grains of sand, glued 

 together round a mucous sheath. We have frequently observed the mode of formation, 

 which is thus effected : Single grains c f sand are taken up by the points of the long 

 extensible tentaculii, Avhich are then folded back upon the body to deposit their load, in 

 apposition with the part of the tube, which is already formed. They are not, however, 

 at once placed in close contact with the perlected part of the tube, but arranged around 

 detached centres, on the surface of the body, (like the developraejit of bone from points 

 of ossification,) and then pushed backward^, by Avithdrawing the body within the tube 

 and hooking the tentacula over the margin. At intervals, the animal moves up and 

 down the inside of the tube, apparently to deposit the mucus exuded from the surface of 

 the body, and so to increase the density of the lining membrane of the tube. — En. 



f Upon the; whole, this distribution will be found equally ai)plioable to our coast ; but 

 it must be taken iu.a general piouit of vkw..— £i). 



