544 liEV. T. K. B. SXEBBING ON CHUSTACBANS [Maj 22, 



information available. Dana gives a detail-figure of the appen- 

 clao-e in question for his E. pellacida and his E. splendens, but it is 

 the latter rather than the former that agrees with the figure 

 delineated by Sars for his E. hideiitata. Of Dana's four species, 

 as judged by the figures, it is only superba which has the tbird 

 joint of the last (developed) leg longer than the fourth. 



It has been already intimated that the limbs, in spite of their 

 general resemblance, are by no means all of one pattern. It may 

 be added that in the second maxiliipeds there is an apical arma- 

 ture which may not be in all species identical. 



12. The brancJiice. — The importance of differences in this appa- 

 ratus is noticed both by Sars and Dana. 



13. First and second pleopods of the male. — Characters derived 

 from these organs appeal chiefly to highly skilled observers, and 

 are not by any means always at their disposal. 



14. Uropods and telson. — Characters, perhaps of not overwhelm- 

 ing importance, are derived from the lengths of the two branches 

 of the uropods in relation one to the other and in relation to the 

 telson, from the number and position of spinules on the telson, 

 and from the smoothness or pectination of the telson's subapical 

 processes. 



So far, then, as at present known, the species will fall into two 

 groups — the first, with the third pleon-segment not produced into 

 a tooth, comprising pellucida, splendens, gracilis, superba, miillei^i, 

 bidentata, similis, murrayi, antarctica, latifrons; the second, with 

 the third pleon-segment produced into a tooth, comprising mmro- 

 nata, gibba, spinifera, gibboides, pseudogibba, schotti, vallentini. In 

 each group there are some well-marked species, but others to 

 which the facilities of a synoptic arrangement cannot be very safely 

 applied. Without attempting, therefore, here to formulate such a 

 table, I will only offer some characters by which closely coupled 

 forms may be distinguished one from the other, or by which parti- 

 cular species are distinctly ear-marked. 



In the first group we observe: — 



With subquadrate rostral projection E. latifrom Sars. 



With broadly triangular rostral projection E. antarctica Sars. 



With very small eyes E. gracilis Dana. 



With two teeth on each lateral margin of carapace E. bidentata Sars. 



E. similis Sars is obviously so named from its 

 supposed likeness to E. bidentata, from which it is 

 distinguished by the unideutate margins of carapace, 

 and inner branch of uropods shorter than outer. 

 Lateral margin of carapace not dentate ; uropods 



reaching beyond telson E. superba Dana. 



Lateral margin of carapace unidentate ; uropods 



not reaching beyond telson E. murrayi Sars. 



In K pellucida Dana and E. mvlleri Claus the 

 inner ramus of the uropods reaches beyond the 

 outer, but not so in E. splendens Dana. In 

 E. pellucida the last three joints of the third 

 perseopod are much shorter than the preceding joint, 

 but not 80 in E. milUeri. 

 [28] 



