NUDIBRANCHIATE GASTEROPODA. 



7 



jected in a length of 0'i6 mra and with a diameter of 0'o8 mm from the anterior genital aperture; it was 

 on the foremost part of the outside and inwardly covered with apparently irregularly arranged (fig. 22) 

 colourless, straight, and a little bent thorns of a height of 0-007 — o-oi6 uim , rising from a little flat base 

 (fig. 23) '). The thorny armatnre is continued for a (short) way into the seminal dnct. 



Fam. Bathydorididae. 



R. Bergh, System 1. e. 1892. p. 1090. 



Bathydoris, Bgh. 



Report on the Nudibranchiata. Challenger-Exped. Zool. Vol. X. 1884. p. 109. 



Corpus fere semiglobosum, sat molle; dorsum papillis couicis parvis ubique sparsis praeditum, 

 margine palliali vix ullo; rhinophoria retractilia clavo perfoliato; tentacula sat magna, nonnihil appla- 

 nata, acuminata; branchia e fasciculis discretis complnribus (6 — 10) frutieulosis 11011 retractilibus for- 

 mata; podarium sat latum. 



Bulbus pharyngeus permagnus; armatura labialis nulla; mandibulae magnae, sat applanatae, 

 margine masticatorio laevi, processu masticatorio uullo; series radulae multidentatae, deute mediano 

 et dentibus lateralibus liamo forti obliquo instructis praeditae. 



Penis fortis, inermis, fissura laterali coeea, apertura apicali. 



This genus was established on a specimen taken during the Challenger Expedition almost in 

 the middle of the Pacific from a depth of 2425 fathoms where the temperature was i° C. 



By the semiglobular form of the body, the separate branchial tufts, and the papillae spread 

 over the back, the Bathydoridae remind not a little of the, otherwise far different, genus Kalinga be- 

 longing to the Polyeeradae, as also, by the position of its branchial tufts, of the Hexabranchidae 2 ). The 

 gigantic bulbus pharyngeus differs essentially from that in all other Dorididae; it is provided with 

 powerful lateral mandibles as those in Bornella and Scvllaca , and as in these genera the}' are on 

 the fore side covered by a thick muscular plate. The armature of the tongue resembles that in 

 the Tritoniadae. As in Bornella and Scyllaca the hermaphrodite gland is quite separated from the liver. 



The Bathydoridae appear to form a remarkable connecting link between the Dorididae and the 

 Tritoniadae, showing also a certain resemblance to the Bornellae and Scyllaeae; but they have also, as 

 other Dorididae, a blood-gland close to the central nervous system. 



The Ingolf-Expedition has from the sea-bottom in the Davis Strait brought, as it would seem, 

 a new form of this genus, which accordingly now comprises 



1. B. abyssorani. Bgh. 



I.e. 1884. p. 109— 116. PL XII, fig. 14 — 20; pi. XIII, fig. 1 — 26; pi. XIV, fig. 15. 



M. pacific. 



2. B. Ingolfiana, Bgh. 



M. atlant. arctic. 



>) I have formerly overlooked this armature, which is only to be discovered with great difficultv. 



-1 The number of gills seems in the BathvdoridEe to be much varying; as the tufts, of which die gills are composed, 

 ma3" be more or less independent, as is also the case in the Hexabranchidae. Comp. my malacolog. Enters.- Heft. XIII. 

 1878. p. 561 ; Heft. XVI. 18S9. p. 929. 



