74 PROCEEDINGS OF THE ACADEMY OF [1879. 



the teeth of the radula comb-shaped, not emarginated in the mid- 

 dle. The genus is unarmed. 



The spawn of the typical species is known, 1 and something of 

 the development. 



Only a few species of this genus are hitherto known, and very 

 likely the Pacific forms will not prove specifically distinct from 

 the typical species, which is found widely spread over the northern 

 part of the Atlantic, on the coasts of America as well as of 

 Europe. 



1. Aeolidia papillosa (L.). 



Gould, Inv. Mass., ed. Binney, p. 240, PL XVIII. f. 258, 1870. 

 Meyer and Mobius, Fauna der Kieler Bucht, I. p. 29, f. 9, 10, 1865. 



Hab. Oc. Atlant. septentr. 



2. Aeolidia serotina, Bergh. 



R. Bergh, Beitr. zur Kennt. der Aeolidiaden ; Verb, der K. K. Zool- 

 bot. Ges. in Wien, xxiii. 1873, p. 619. 



Hab. Oc. Atlant. septentr. 

 1. Aeolidia papillosa (L.). 



Hab. Oc. Pacificum (Sanborn Harbor, Nagai, Shumagin Islands, 

 Alaska Territory). 



Only one specimen of this species was taken by Ball in July, 

 1872, in Sanborn Harbor (Shumagin Isl.) at low water on rocky 

 bottom. 



According to Dall the color of the living animal was j'ellowish- 

 white ; the color of the animal preserved in spirits was also uni- 

 formly 3 r ello\vish-white. The length was about 15.0 mm., with a 

 breadth of body of 9.0 and a height of 5.0 mm., the breadth of 

 the foot 5.5, the length of the papilla? 4.5, the length of the rhino- 

 phoria and of the tentacles about 2.0 mm. 



The form of the (rather contracted) animal was nearly that of 

 the Ae. papillosa, in general and in most particulars ; the papillae 

 were set in very many oblique rows, closely crowded. 



The central nervous system showed the cerebro-visceral ganglia 

 rather elongated, the pedal ones of rounded form, more than half 

 as large as the former; the subcerebral, the pedal, and the visceral 

 commissures as usual, the latter with the N. genitalis. The buc- 

 cal ganglia elongate, of nearly semi-oval form, the commissure 



1 Alder and Hancock, Mon. Brit. Nud. Moll., Part VI., fam. 3, pi. 9, f. 6. 



