8CHIZOPODA. 



said to have reached that state. Still, they afford material for a re-description and 



figures of the species in the adult state, with some notes on the growth change-. 



The Mvsidacea consist of eleven specimens, referable to six species. The most 

 interesting of these species is Hansenomysis inifnn 4 fii-,i, an Antarctic representative of 

 a genus hitherto known from hut three specimens from Arctic and Itoival waters. 



The chief interest of the collection lies in the evidence which it may afford as to 

 the similarity or dissimilarity of the fauna at the two poles. There are no species 

 common to the fauna of both polar regions in the collection : but, on the other hand, 

 all the genera save one, Antarctomysis, are represented in northern waters bv species 

 which are quite distinct from their southern allies. 



Exploration of the bottom fauna of the, deep waters of the nlolic. especially in 

 tropical and sub-tropical regions, is as yet only in its infancy, and it is therefore 

 extremely probable that what are now known to be bipolar genera and species will in 

 future be found to be cosmopolitan in their distribution. The8chizopoda were long 

 thought to have in Lophogaster fj/jiicux a stock instance of a bipolar form, but tin- 

 gaps in its distribution have been almost completely filled up as a result of recent deep- 

 sea work, and, with the exception of the tropical Atlantic, its range is known to be 

 complete from Norway to the < 'ape. 



Two bipolar species of Mysidse are known, however Boreomysis scyphops, C,. < ). 

 Sars, from Arctic waters, and Lat. 50 S. , near the Crozet Islands, and Ani/>/>/t>jix 

 crozetti, from the seas of Ureeuland and Ian Mayeu in the north and the Crozct Islands 

 in the south. They are not known from the intermediate waters. 



Of the genera of Antarctic Schixopoda, EH-II/KIHX/H, Tlii/xini<>; : x<i, and l^n-ajiin arc 

 world-wide in range, but the northern and southern species arc quite distinct, even tin- 

 hitherto supposedly cosmopolitan Etii-njiit/ mixfrtilix. Ilansen having shown (o contain 

 at least two species, probably three. 



Ps'eudomma, Hansenomysis, Dactylamblyops, and Mysidetes are. as at pn-.-cm 

 known, bipolar genera, but Pseudomma, at least, ranges far from both poles, and 

 further exploration will probably extend the known range of the other genera also. 



The most interesting case is presented by the genus Antarctomysis. It is c|o>el\- 

 related in structure to the northern species Michtheimysis mixta (Lilljeboig), a species 

 inhabiting chiefly the colder waters of the northern hemisphere. The two genera are 

 separated only in the characters of the male pleopods. which arc more primitive in the 

 Antarctic form, and neither genus is likelv to be found to have a distribution which 

 extends very far from the poles they frequent. 



In the preparation of this report 1 have received miicli valuable help from manv 

 sources. The authorities of the British .Museum kindly allowed me to examine and 

 dissect two specimens from the Challenger' collections in their charge. To 1 'r. 

 (',-ilman, of the British Museum, I have been much indebted for information on manv 

 points connected with the Challenger' material, and he has. also, at my reqiu-.-t. 

 furnished me with drawings of various species. Mr. Iv \V. 1,. HO|I kindly examined 



