12 SIR CHARLES ELIOT. 



BATHYDORIS (BERGH). 



(Bergh, Chall. Report Nudibr. (1884), p. 109 ; id., Ingolf Exp. Nudibr. (19), p. 7.) 



THIS remarkable genus is in many ways a link between the Tritouiidae and Dorididee. 

 The shape is spherical, and the back bears deciduous papillae. The head parts are much 

 as in the Dorididse ; the rhinophores perfoliate and non-retractile. The branchiae 

 consist of separate non-retractile tufts, set in a circle on the posterior part of the back. 

 The powerful jaws and radula are much as in the Tritoniidae. The hermaphrodite 

 gland is separate from the liver. In the nervous system the cerebral and pleural 

 ganglia are distinct and not fused. 



Only four specimens of this genus are recorded, constituting as many species : 



1. B. abyssorum Bergh, obtained by the ' Challenger ' near New South Wales, in a 

 depth of 2,425 fathoms. 



2. B. ingolflana Bergh, from Davis Strait, in 1870 fathoms. 



3. B. hodgsoni spec, nov., from the Antarctic, in 100 fathoms. 



4. B. inflata spec, nov., from the Antarctic, depth not stated. 



It is noticeable that this genus, which is only recorded from great depths in 

 northern and temperate seas, is in the Antarctic regions found in comparatively shallow 

 water. 



The Antarctic forms agree with those described by Dr. Bergh in most points, but 

 differ in several details, among which may be mentioned the presence of numerous 

 papillae along the dorsal margin and over the mouth. Unfortunately it is difficult to 

 give a complete and satisfactory description of either, for B. hodgsoni, though well 

 preserved internally, has probably been somewhat distorted externally, while B. inflata 

 appears to be excellently preserved externally, but has no internal organs in a 

 recognisable condition except the teeth and jaws. The two appear to be specifically 

 distinct, as the radulse are different and, as it would seem, the tentacles and branchiae as 

 well. B. hodgsoni is best characterised as having an armature of small black spines in 

 the stomach and large solid tentacles at the side of the head. B. inflata has smaller, 

 grooved tentacles, very small, easily detachable branchiae, and comparatively few dorsal 

 papillae. 



Dr. Bergh gives as a generic character rhinophoria retractilia. This is possibly a 

 slip, for neither his descriptions nor his figures are quite decisive on the point. But 

 there can be no doubt that in both of these species, and also in B. abyssorum (the 

 specimen of which preserved in the British Museum I have examined) the rhiuophores 

 are not retractile, that is to say, there are no pockets into which they can be with- 

 drawn, 



4. BATHYDORIS HODGSONI (Figs. E-G). 



ONE specimen captured in 100 fathoms off Coulman Island on January 13th, 1902, 

 As preserved che colour is orange yellow of varying shades. Though the animal is not 



