TATTERSALL— MYSIDACEA AND EUPHAUSIACEA 129 



T. agassizii, Hansen, 1910. 

 T. monacantha, Hansen, 1911. 



Stations. C, 1200—0 fms., two, 20 mm.; q, 1000—0 fms., three, 12 — 19 mm.; 

 s, 750 — 500 fms., one, 23 mm.; 11, 750 fms., eighteen, 13 — 28 mm.; mm, 400 fms., fifteen, 

 17 — 24 mm.; nn, 200 fms., three, 24 mm. 



I had already named these specimens as T. monacantha, Ortmann, when I received 

 Hansen's report on the Sihoga collections. In this report Hansen had regarded T. mona- 

 cantha and T. agassizii as distinct though very closely allied forms, but in his most recent 

 paper (1911) he has arrived at the conclusion that their separate specific identity cannot 

 be maintained. With this conclusion, I am in entu'e agreement. I give (fig. 8) a figure 

 of the copulatory apparatus on the first pleopod of the largest male in the collection. 

 Dr Hansen has seen this figure and is inclined to think that the specimen from which 

 it was taken is immature. 



18. TJiysanopoda microphthalm,a, G. O. Sars. 



T. microphthalmia, Sars, 1885. 



T. distinguenda, Hansen, 1905. 



T. distinguenda, Holt and Tattersall, 1906. 



T. microphthalma, Hansen, 1910. 



Stations, s, 500 — 750 fms., one female, 18 mm.; 11, 750 fms., one female, 31 mm.; 

 mm, 400 fms., four females, 20 — 27 mm. and one male (immature), 20 mm. 



The only male specimen is immature so that the structure of the copulatory organs 

 cannot be ascertained. This renders the identification of the species very uncertain. 

 I have very carefully compared these specimens with Atlantic representatives of 

 T. microphthalma and I am unable to find any appreciable difterences between them. 

 But I cannot overlook the possibility that the Sealark forms may be T. onentalis, 

 Hansen, a species very closely allied to T. microphthalma and only distinguishable by 

 the structure of the first pair of pleopods in the male. 



19. Thysanopoda pectinata, Ortmann (Plate 7, fig. 7). 



T. pectinata, Ortmann, 1893. 

 T. pectinata, Hansen, 1905 (2). 

 T. ctenophora, Illig, 1908 (1) [jide lUig, 1908 (2)). 

 Parathysanopoda foliifern, Illig, 1909. 

 T. pectinata, Hansen, 1911. 

 Stations. N, 600 — fms., one female, 18 mm. ; U, 750 fms., one male, 33 mm. 

 I had already named these specimens as T. pectinata, Ortmann, when Hansen's 

 report on the Sihoga collections came to hand. On consulting him with reference to 

 these specimens, he told me that he believed they represented a new form, distinguished 

 from T. 'pectinata by the somewhat longer and more acute rostrum. In his recent paper 

 (1911), however, he has expressed the opinion that the Pacific and Atlantic forms are 

 specifically inseparable. This confirms my earlier conclusions as to the name to be 

 attached to the Sealark specimens. 



SECOND SERIES— ZOOLOGY, VOL. XV. 17 



