542 REV. T. R. R. SXEBB1NG ON CRUSTACEANS [May 22 



very small, and obtusely rounded." In Dana's detail-figure the 

 beak in question is apically einarginate ! 



2. Lateral denticles of carapace. — Of these there may be on, 

 or approximate to, each side margin two, or only one, or none. 

 "When present they are not easily perceived without separation of 

 the delicate carapace from the body of the animal. They are not 

 mentioned or figured by Dana in an)' of his four species, but attri- 

 buted by Sars to three out of those four, Bars finding them in all 

 species except superba Dana and his own antarctica and latifrons ; 

 Ortmann also finding them in his three new species described in 

 1893. Only one species has two denticles on each side, namely, 

 E. bidentata Sars. In E. mulleri Claus gives no clue to their 

 presence. The single denticle is usually near the middle of the 

 margin, but in murrayi Sars it is in front of the middle, and in 

 spinifera Sars behind it. 



3. Third segment of pleon ivith a medio-dorsal backward pro- 

 jection. — This character is common to mucronata, gibba, and spini- 

 fera, established by Sars, and to gibboides, pseudogibba, and schotti, 

 established by Ortmann, and to the new species here described. 



4. Length of sixth pleon-segment in relation to that of fifth, or 

 of fifth plus fourth, or of the telson ; the shape of the postero- 

 lateral corners of the fifth segment ; and the character of the 

 postero-dorsal margin in this and the preceding segment. 



5. The compressed ventral tooth at distal end of sixth pleon- 

 segment, called the pre-anal spine. — This is unnoticed by Dana 

 and Claus, but present in all the species described by Sars and 

 Orlmann, except murrayi Sars, supjerla Dana, mucronata Sars. 

 and schotti Ortmann. It is said to be simple in all the other species 

 except bidentata Sars, in which it is tridentate ; spinifera Sars, 

 in which it is bidentate (as occasionally also in gibba Sars) ; and 

 pseudogibba Ortmann, in which it is described as 2-4-dentate, 

 rarely simple. In the new species of this paper it is tridentate, 

 at least usually. The variability to which this character seems to 

 be liable is very detrimental to its value. 



6. Dimensions of the eyes. — The smallness of the eyes is charac- 

 teristic only of gracilis Dana aud Sars, gibba Sars, and pseudogibba 

 Ortmann. Dana shows it in the figure of his species, without 

 mentioning it in the text. Ortmann, who contrasts small eyes 

 with eyes " tolerably large," makes the comment : " This distinction 

 is apparently dubious ; with some practice, however, the size of the 

 eyes in relation to the body is easy to estimate and essentially 

 determines the habitus of the species." One cannot help noticing 

 that between gibboides Ortmann and pseudogibba Ortmann, both 

 occurring in the same localities, there is scarcely any appreciable 

 difference except in the size of the i ody and the size of the eyes. 

 The smaller eyes pertain to the smaller species ; and though the 

 inferiority in the dimensions of the eyes is relative as well as 

 absolute, some suspicion must still attach to the validity of Ortmann's 

 pseudogibba until fuller details are given for separating it from 

 gihboidn;. 



