1879.] NATURAL SCIENCES OF PHILADELPHIA. 91 



of Nudibranchiata with a ramified liver, and those with a simple 

 liver embracing the Dorididse and the Porostomata 1 (Do?-iopsidse, 

 Phyllidiidse). 



As in the Dorididse there is only one spermatotheca ; but in the 

 general form of the body, and in the nature of the pharyngeal 

 bulbus they show more affinity to the Porostomata. 



The family seems to include but one genus, the proper Tritonise ; 

 two other established genera, the Candiella of Gray (Fig. Moll. 

 An. iv. 1850, p. 106), with Tr. plebeia as type, and the Nemo- 

 cephala of A. Costa (Atti della R. Acad, delle Sci. di Napoli, iii. 

 No. 19, 1869) with the new (?) species (N. marmorata, C.) as type 

 very likely merge in the typical genus, at least the characters 

 given by these authors do not raise these forms to new generic 

 rank. 



The animals belonging to this group are all slow, sluggish, and 

 voracious. The spawn of the northern European species has been 

 made known b\' Dalzell, Alder, and Hancock ; of the develop- 

 mental history nothing is hitherto known. 



This group seems not to belong to the tropical seas. A small 

 series of species has been published from the eastern part of the 

 Atlantic (while only one is yet known (?) from the western), from 

 the Mediterranean, the Red Sea, and the northern part of the 

 Pacific. 



1. Tritonia Hombergi, Cuv. N. Atlant. 



2. Tr. rubra, Leuck. Rupp. Atlas, 1828, p. 15,' t. 4, fig. 1. 



3. Tr. elegans, Sav. Egypte, xxii. PI. II. fig. 1, 1827. 



Tr. glaucce, Leuck. Rupp. Atl., p. 16, t. 4, fig. 2, 1828. Mare Ru- 

 brum. 



4. Tr. cyanobranchiata, Leuck, Rupp., 1. c, p. 16, t. 4, fig. 3 a, b, Mare 



Rubrum. 



5. Tr. decaphylla, Cantr. Bull, de l'Ac. des Sci. de Brux. 11, p. 384, 1835. 



Tr. quadrilatera Schultz, Phil. En. Moll. Soc, i. p. 103, t. xix. fig. 



2 ; ii. p. 76. 

 ? Tr. Blainvillea, Risso, Eur. Merid. iv. p. 35, 1826. Verany, Journ. 



de Conchyl. iv. p. 386, 1853 2 (unpublished). 

 ? (Juven.) Tr. gibbosa, Risso, 1. c. p. 35. Mare Mediteran. 



1 I have used this name for a group including the Doriopsidm and PTiyl- 

 lidiidm ; cf. my Mai. Unters. x. 1876. 



2 The species is named, but not described. The cited book of Verany 

 has never been published. Last year a young friend, M. Vayssiere, of 

 Marseilles got some specimens from the family and kindly sent me one. Cf. 

 my Mai. Unters., xiii. 1878, p. 530. 



Va> 



