SYSTEMATIC REPORT 59 



regarded as of generic significance and the definition of the genus may be summarized as follows: 

 Anterior margin of carapace rounded and uptilted, forming a very short upturned rostrum; proximal 

 segments of the outer flagellum of the antennule in the male very enlarged ; antennal scale oval, un- 

 segmented, outer margin armed with spines among the setae or with an evenly graduated row of spines 

 and no setae ; exopods of first pair of thoracic appendages absent ; endopods of third to fifth pairs 

 slender, each terminating in a minute ' chela ', formed by the dactylus impinging on a strong spine at 

 the distal end of the propodus; endopods of sixth to eighth pairs terminating in a long slender claw; 

 pleopods in the male biramous with the endopod modified in the first and fifth pairs, in the female 

 reduced and uniramous ; outer margin of proximal segment of the exopod of the uropod armed with 

 spines among the setae, or with a close row of spines and no setae. 



In all the known species of the genus there is a peculiar rounded depression partially covered by 

 a thin membranous flap on the dorsal surface of the proximal end of the first segment of the antennular 

 peduncle. 



The genus has certain primitive characters, such as the absence of an exopod on the first thoracic 

 appendage, the absence of a statocyst on the uropods and the presence of seven pairs of oostegites 

 in the marsupium of the female. It is less primitive than genera of the family Lophogastridae in the 

 absence of gills on the thoracic appendages and in the reduction of the pleopods in the female and the 

 modification of certain pairs in the male. 



Hansenomysis antarctica Holt and Tattersall, 1906 



(Fig. 8A-F) 



19066 Hansenomysis antarctica Holt and Tattersall, p. 6. 

 1908 Hansenomysis antarctica, Tattersall, p. 23, figs. 



1913 Hansenomysis antarctica, Hansen, p. 8, fig. 



1914 Hansenomysis antarctica, Zimmer, p. 385, fig. 



Occurrence : 

 St. 181. 12. iii. 27 (day). Schollaert Channel, Palmer Archipelago, 335-160 m., 1 adult S (the distal end of the 

 telson is missing and the length from the anterior margin of the carapace to the fractured margin of the telson 

 is 23 mm.). 



Remarks. Tattersall (1908, p. 23) gave a very full account and clear figures of this species, which had 

 been founded on two adult females, captured off Coulman Island in the Antarctic. Unfortunately the 

 posterior end of the telson was missing in both specimens and the figure of this organ given by Tattersall 

 was a composite one built up from these specimens and from fragments of the same species taken in the 

 same haul. Since then only two specimens of the species have been recorded, an adult male off 

 Graham Land (Hansen, 1913, p. 8) and a single specimen, of which the sex was not recorded, in 

 66° 2' S., 89 38' E. (Zimmer, 1914, p. 385). In Hansen's specimen the distal portion of the telson was 

 missing. Zimmer's record was very brief and no mention was made of the form of the telson. 



Only one specimen of the species was collected by ' Discovery ', an adult male from the Schollaert 

 Channel in the Palmer Archipelago, and, unfortunately, in this specimen also the distal portion 

 of the telson is lacking. However, a considerable portion is present and shows the lateral margins to 

 be straight and almost parallel with no sign of a broadening towards the apex, such as is shown in 

 Tattersall's figure. 



The Discovery specimen shows certain differences from the published descriptions and figures and, 

 had the species been based upon perfect animals, I should have hesitated to refer this present example 

 to H. antarctica. However, I think that these differences can be attributed to the mutilation of previous 



