258 REV. T. R. R. STEBBfNG ON STALK-EYED CRUSTACEA MALACOSTRACA 



The generic name Dorynchus depended not on a definition but on the dorsal view of 

 a specimen. The word Lispognathus, signifying " a smooth jaw," is not very appro- 

 priate for Norman's species, in which the large third joint of the external maxillipeds 

 is well studded with tubercles. Further, it has been shown by Doflein that in respect 

 of length and divergence the rostral spines of Dorynchus thomsoni are very variable, 

 so that its removal to Achseopsis is made the less difficult, and two rival claimants 

 to the generic name may conveniently be dispensed with. 



Achseopsis thomsoni (Norman). 



1873. Dorynchus thomsoni, Norman, Depths of the Sea, p. 174, fig. 34. 



1880. Lispognathus furcillatus, A. Milne-Edwards, Crust. Mexic, p. 349, pi. xxxiA. fig. 4. 



1886. Lispognathus thomsoni, Miers, Rep. Voy. " Challenger;" vol. xvii. part xlix. p. 28, pi. v. fig. 2. 



1886. ,, ,, Perrier, Explor. sous-marines, p. 298, fig. 218. 



1900. „ ,, A. Milne-Edwards and Bouvier, Crust. Decap. " Travailleur-Talisman," 



p. 148, pi. iii. fig. 8, pi. xxi. figs. 8-14. 

 1904. ,, ,, Doflein, Ergebn. Deutschen Tiefsee-Exp., vol. vi. p. 75. 



1908. ,, ,. Hansen, Ingolf-Exp., "Crust. Malac.," vol. iii. part ii. p. 11. 



1910. Dorynchus thomsoni, Stebbing, Annals S. Afr. Mus., vol. vi. part iv. p. 286. 



1911. Achseopsis thomsoni, Rathbun, Tr. Linn. Soc. London, vol. xiv. part ii. p. 247. 



A. Milne-Edwards and Bouvier in 1900 still regard L. furcillatus as specifically 

 distinct (loc. cit., p. 148), and on pp. 151, 152 (twice by a slip calling it L. furcatus) 

 say that " L. thomsoni is distinguished from L. furcillatus by the more slender form 

 of the carapace, narrow front, rostral spines less divergent, spines of carapace more 

 marked." Doflein with ample material decides that the differences are based on a 

 young specimen. Miss Rathbun says of an adult male example taken at Seya de 

 Malha from a depth between 300 and 500 fathoms: "This example has parallel 

 horns about a quarter as long as remainder of carapace. It differs from typical 

 specimens in having the anterior gastric and anterior branchial spines obsolete or 

 reduced to low tubercles. The species is very close to A. spinulosus, Stimpson 

 (Smithson Misc. Coll., xlix., 1907, p. 21, pi. iii. figs. 5, 5a), which has shorter legs, 

 described as minutely spinulous above, but there is no indication, in description or 

 figure, of the terminal spine on the merus joints. A. spinulosus is an inhabitant 

 of shallower water (10 fathoms in Simon's Bay, Cape of Good Hope)." As sug- 

 gested above, the conspicuously long legs of A. thomsoni seem to separate it de- 

 cisively from the other species of the genus. But if A. spinulosus has anything 

 like the variability established for A. thomsoni, the validity of A. gilntheri must be 

 regarded as resting on a very insecure foundation. 



The Scotia specimens have a denticle at the middle of each of the divergent 

 rostral horns and a larger subdistal one visible from below. The eyes have a 

 tubercle on the peduncle and another subdistal on the corneal portion. In the 

 first antennae the third joint of the peduncle is oval, wider than the preceding joint; 

 the principal fiagellum carries numerous filaments. The palp of the mandibles 



