Note on the structure and relations of the kidney in Aplysia. 421 



corresponding in almost eveiy respect witli the » triangulär gland « of 

 Aplysia. Notarchus may be described as an Aplysia, in wbich the lateral 

 lobes have fused together along their free edges above the mantle from 

 behind forwards , a small aperture being left anteriorly, by which the 

 Chamber so formed communicates with the exterior. When these fused 

 lobes are cut away, the upper surface of the mantle is seen quite bare 

 with the pericardium in front and behind it the kidney, which though 

 relatively smaller than in Aplysia, is still of considerable size. 



I have not been able to consult Cuvier's Memoirs on Mollusca, as 

 the library of the Zoological Station does not possess a copy of them, but 

 the figures of the anatomy of Aplysia in Bronn's Thierreich \ which are 

 taken from that work, are not clear as to the relations of the renal organ. 

 There is a reference letter to the opening of the renal organ in the de- 

 scription of the piate, which cannot be found anywhere in the piate itself. 

 In the text all that is said of the kidney, is that its external opening is 

 situated beueath the branchia , a statement which is taken from an in- 

 cidental remark of Lacaze-Duthiers in bis Memoir on Pleurobranchus 

 aurantiacus^. 



The nomenclature of the species of Aplysia is somewhat uncertaiu. 

 The examples which I have used in the Zoological Station belong to 

 two large species which are both very pleutiful : they are known by the 

 names Aplysia leporina and Aplysia depilans. The size of these is 

 usually about 6 inches in length and 3 or 4 in breadth and height. 

 There is a :V^ species common at the Station which is much smaller, 

 not exceeding I1/2 inches in length. The first of the three mentìoned is 

 black in color, with white fiecks bere and there, which are caused by 

 groups of small opaque white spherules in the skin ; it is usually the 

 largest in size, it is flaccid when handled, and possesses very little 

 muscular power : its lateral lobes are easily spread open and are only 

 slightly fused together behind. It gives out from the cutaneous glands 

 on the under surface of the free lobe of the mantle a large quantity of 

 purple fluid, and its poison gland has a single external opening, which 

 is small and circular in shape and is situated behind and to the right of 

 the geuital aperture. In giving out a purple fluid and in having a 

 common aperture for the poison glands, this form agrees vrith the A. 

 fasciata , camelus and Neapolitana of Delle Chiaje, and therefore it 

 will be conveuieut to cali it as Dr. Blochmann does, A. camelus Cuv. 



> Keferstein, Weichthiere. 1862— 18Ü6. Taf. LXV. 

 2 Ann. Sci. Nat. 4th Ser. Voi. XI p. 257. 



