SYSTEMATIC REPORT 45 



latitude 30 S. in a haul (in which the net failed to close) from 1050 m. proves that it can tolerate much 

 lower temperatures than Fage supposed. It has previously been taken at the bottom and if it was 

 taken at the bottom in the haul at station 440 it would have been living at a very much greater depth 

 than has previously been known for it. The temperature at 1000 m. was 7-67° C. at the time of capture. 



Lophogaster schmidti Fage, 1941 



1941 Lophogaster schmidti Fage, p. 34, figs. V &• J / 



Occurrence : 



St. 1585. 1. v. 35 (night). South east of Ras Hafun, 500-0 m., 1 ovig. $, 19-2 mm. 



St. 1587. 3. v. 35 (night). Off Ras Hafun. Two hauls: (i) 450-0 m., 3 <$<$, 14-16-4 mm., 3 ??, with very small 

 oostegites, 14 mm., 4 juv. ; (ii) 1250-800 m., 1 juv., 11 mm. 



Remarks. These specimens agree in every respect with the types. Fage (1942, p. 34) stated that 

 in the female there were 10- 11 spinules arming the apex of the telson between the long apical spines 

 but that in the male there were only 9-10. The three males in the Discovery collection are very 

 immature but there are eight spinules on the apex of the telson with two minute traces of spinules. 

 In most species of the genus the eighth thoracic appendage is smaller than the preceding ones. In 

 L. schmidti the reduction of this appendage is particularly marked and its exopod is extremely small 

 (Fig. 3 D, cf. C). The four pairs of spines arming the lateral margins of the telson are very small and 

 in most cases the three anterior pairs can only be seen with difficulty, their presence being indicated by 

 the small indentations which mark their sockets. When they do attain any length they are very fine 

 and delicate. The penultimate pair near the apical spines are smaller than is usual in other species of 

 the genus (Fig. 3 E-F). 



Distribution. The types were captured in tropical waters of the Pacific at several stations to the 

 north and west of New Guinea. Fage records that they were pelagic at 100-200 m. over great depths. 

 The Discovery specimens were taken in the West Arabian Sea, off Ras Hafun in oblique hauls from 

 500 m. and 450 m. to the surface. The depth of the sounding at these stations was 5046 m. and 5098 m. 

 respectively, so that precisely the same conditions prevailed as those in which the type specimens were 

 captured. 



Family Eucopiidae 



1852 Eucopia Dana, p. 609. GenUS EuC ° pia Dana ' l8 5 2 



Remarks. A great deal of confusion has arisen in the identification of specimens of Eucopia, much 

 of it due to the fact that as growth proceeds considerable changes take place in the proportions and 

 armature of the various parts. Even after sexual maturity has been attained, growth and the accom- 

 panying growth changes continue. 



I have discussed the validity of the various species of the genus in the 'Monograph on British 

 Mysidacea' (Tattersall and Tattersall, 195 1, pp. 97-9), especially with regard to those forms which 

 occur in British waters. I regard the following four species as established: australis, unguiculata, 

 sculpticauda and grimaldii. The Discovery material furnishes additional evidence of the variations due 

 to growth which have caused so much confusion in the past, and includes forms not recorded from 

 British waters. Some further remarks on the subject are therefore necessary. 



Of the four species named above, E. sculpticauda is the most easily recognized, thanks to the careful 

 work of Illig (1930, p. 400) who described and figured the growth changes which occur with the onset 

 of maturity. These result in the clearly defined specific characters of the adults, which differ widely 

 from those of very immature animals. E. sculpticauda can be readily identified at all ages by the 



