TATTERS ALL— MYSIDACEA AND EUPHAUSIACEA 127 



very wide and unarmed, so that the distal part of the telson has the form of a two-pronged 

 fork ; lateral margins armed along the distal two-thirds of the margin with six spines, 

 three of which are on the forks of the prong, the distal one at the tip. 



Uropods long and slender, about one and a third times as long as the telson, the inner 

 one very slightly longer than the outer, without spines on its inner ventral margin. 



Length of an adult male, 5 "5 mm. 



I have been somewhat puzzled as to what genus this species should be referred to and 

 after much hesitation I have placed it in the genus Anisomysis, Hansen, as being the one 

 with which it agrees most closely in its main features. It differs in having the tarsus of 

 the thoracic limbs apparently undivided and in the striking form of the telson. In having 

 the outer terminal branch of the fourth pleopods in the male unjointed it also presents a 

 small point of difference. But otherwise it agrees so closely with Hansen's type species, 

 the only one known*, A. laticauda, that I have preferred to refer it to the same genus 

 rather than erect a new one for its reception. The form of the telson will at once serve 

 to distinguish it from all known Mysidae. 



Species of uncertain generic position. 



14. " Mysis" quadrispinosa, IHig (Plate 6, figs. 6, 7). 



M. quadrispinosa, Illig, 1906. 

 Stations. I, north of the Chagos Islands, 500 fms., one female, 5 mm. ; M, Chagos 

 Islands, 75 fms., one female, 3 mm. 



This species was described by Illig from a female captured at the Chagos Islands by 

 the Valdivia expedition, and lUig rightly left its generic position unsettled till male 

 specimens should be taken. The present specimens were captured in the same locality as 

 lUig's type and appear to be the same species, but since both specimens are females and 

 stiU immature, it has not been found possible to throw any light on its generic affinities. 

 I am able, however, to add one or two particulars to lUig's brief description which will 

 serve for the better elucidation of its characters. 



The pleon is distinctly hispid all over and has the first five segments subequal in 

 length, the sixth being almost twice as long as the fifth. 



There does not seem to be any hispidity on the thorax. The carapace is produced 

 into a short acutely pointed rostral projection which reaches about half way along the first 

 joint of the antennular peduncle. 



The antennal scale is slightly longer than the antennular peduncle and twice as long 

 as its own. It is about six times as long as broad, narrowly lanceolate in shape, setose all 

 round and having a small terminal joint. The outer distal corner of the joint from which 

 the scale springs is produced into a short stout spine-like projection. 



The telson (fig. 7) is only slightly shorter than the last segment of the pleon and 

 twice as long as broad at its base. It is deeply cleft for two-fifths of its length, the clefl 



* While this paper was in the press, two furtlier species of Anisomysis have been described from Japan by 

 Nakazawa (Ann. Zool. Japon., vol. vii. pt. iv. 1910). In both species the telson is described as entire and, as 

 such, cannot be confused with the present species. 



