NUDIBRANCHIATE GASTEROPODA. 



. 10 m in The median plates showed on the hooked part outward to each side 2( — 3) denticles (fig. 17a); 

 the lateral plates (fig. 17, 18) were quite as before described. 



Also the salivary glands, the intestinal canal, and the yellow liver were as before described. 



The anterior genital mass was large; the ampulla of the hermaphrodite duct, the seminal 

 vesicles, the two parts of the seminal duct, and the penis-sac were as usual; the armature belonging 

 to the glans penis and part of the seminal duct (fig. 19) showed the thorns in great numbers and 

 of a length of up to 0-030""". The mucous gland was milk-white. 



Fam. Diaululidae. 



R. Bergh, System d. nudibranch. Gasteropoden. 1892. p. 1097 — 1100. 



This (provisional) family includes forms with a somewhat flattened body and most frequently 

 with a finely villous back. The tentacles are of a tubercle- or finger-like shape; the branchial cleft is 

 roundish and most frequently crenate, with tripinnate gill-leaves. - - The labial disk is unarmed. The 

 narrow rhachis of the radula is nakked; its pleurae bear many tooth-plates, and these, at least the 

 greater part of them, are hook-shaped. The penis is mostly unarmed. 



The family contains several rather distinctly marked generic forms. Of the nearly related 

 genera Diaidula and Gargamella the latter is distinguished by a strong armature of the penis (of the 

 same kind as in Platydoris and Hoplodoris). TJwrdisa and Aldisa have small tubercle -like tentacles; 

 but in the former the outermost tooth-plates are comb-shaped, while the tooth-plates in Aldisa are 

 erect, staff-shaped, and the penis armed with rows of thorns. The genus Trippa has the back covered 

 with villous tubercles, and particular salivary glands of the oral tube (gland, ptyalinac). Halgcrda has 

 a smooth back, a narrower foot, and the outermost tooth-plates are serrated. The teeth of the genus 

 Baptodoris are somewhat like those of Halgcrda, but the penis is here armed with series of thorns (as 

 in the Phvllidiadae and the Doriopsidae). The body of Pcltodoris is more stiff, and the back finely 

 granulated. The genus Phialodoris agrees as to the outer form with the last-mentioned genus, but its 

 penis is of a very deviating shape. 



Aldisa, Bgh. 

 R. Bergh, 1. c. 1892. p. 1098. 



Aldisa zetlandica (Aid. et Hanc). 

 Tab. V, fig. 17—23- 



One specimen of this species was taken at station 27 i. e. on 66°33' Lat. N. 20°05' Long. W., at 

 a depth of 44 fathoms (temp. 5°6). 



Preserved in alcohol it measured in length n mm by a breadth of 6 mm and a height of 4 ,mn ; 

 the length of the foot was 9-5'"'" by a breadth of 4-5 mm ; the diameter of the branchial cleft was 2 mm , 

 and the gill-leaves reached to a height of i mm . The colour of the back was a light lemon-colour, 

 but the tubercles were whitish; the rhinophoria and the gill-leaves were yellow; the lower side of 

 the whole body was yellowish white. 



The form was oblong-oval, the lateral edges however rather parallel, the rounded anterior 

 and posterior end of the same breadth. The back was everywhere covered with small; a little pointed 



PO 



