248 niOCEEDTNGS OF THE MALACOLOGICAL SOCIETY. 



The exact dimensions of a medium-sized spirit specimen are : — 



1. Length over back from head to tip of tail, 33 mm, 



2. Length of sole, 31 mm. 



3. Width of hack, 10mm. 



4. Breadth of sole, 3"5 mm. 



5. Breadth of groove hetween sole and hack, 2*5 mm. 



6. Distance of anus from right tentacle, 6 mm. 



7. Distance of anus from pulmonary oriiice, 5 mm. 



8. Distance of jiulmouary oriiice from head, 8 mm. 



Median dorsal groove continued to the head. Anal opening close to 

 foot margin. Genital opening close behind the right tentacle. Young 

 specimens found near Auckland had only an oval space ronnd the 

 pulmonary orifice, coloured dirty yellow ; the others lacked pig- 

 mentation, being semi-transparent, whilst some of the internal organs 

 could easily be distinguished. In alcohol they became opaque like 

 other specimens. 



A. hitentaculatus is the most common species of the genus, and is 

 more abundant in the North Island than in the South, where 

 A. paplUatiis partially takes its place. It is said to occur also on 

 the Chatham Islands, but I have not seen any specimens from that 

 locality. 



2. Athoracophorus antipodum (Gray, em.). 



Janella antipodarum^ Gray: Ann. Mag. Nat. Hist., vol. xii (1853), 



p. 414; and Proc. Zool. Hoc, 1853, p. 112. 

 A. hitentaculatus, aud., fion Quoy & Gaimard. 



The back is more rounded than in A. hitentaculatus, the colour 

 brighter, and spots or dashes of brown or black are entirely absent. 

 Its generative system was described and figured by Collinge ^ under 

 the name of Janella bitentaculata, showing that Athoracophorus anti- 

 pod arum is really distinct. 



Gray does not give any special description of the species, but bases 

 on it the diagnosis of his genus Janella. Cockerell, on examining the 

 type-speciuien in the British Museum, made it a. form of A. hitentacu- 

 latus, saying "the variety differs from the ty\)Q in being without 

 spots." * This evidence shows that Collinge's Janella hitentaculata is 

 really Athoracophorus antipodarum, and that his Janella maculata must 

 be Athoracophorus hitentaculatus. There is only one other species of 

 the section Athoracophorus, A. duhius, which has the same colour- 

 markings as A. hitentaculatus. It differs from the latter, however, 

 in several points, as will be shown further on. 



A. antipodarum. is distinguished from A. hitentaculatus by the 

 absence of darker spots, the more highly rounded back, the long 



Proc. Zodl. Sdc, 1804, pp. 528, 529. 

 Proc. Zdol. SoL'., 1891, I). 217. 



