I. '08. 



118 



allied B. Payeri the species may be distinguished by the fol- 

 lowing characters : — 



B. gracilis. 



Median carina of carapace 

 usually terminating anteriorly 

 in a small tooth. 



Supra-orbital spines more 

 pi'ominent. 



Eye longer, the greatest 

 width of the cornea about 

 half the greatest width of the 

 antennal scale. 



Antennal scale longer than 

 carapace. 



Antennal scale three times 

 as long as wide. 



B. Payeri. 



Median carina of carapace 

 rarely terminating anteriorly 

 in a tooth. 



Supra-orbital spines less 

 prominent. 



Eye shorter, the greatest 

 width of the cornea about 

 one-third the greatest width 

 of the antennal scale. 



Antennal scale not longer 

 than carapace. 



Antennal scale not more 

 than two and a half times as 

 long as wide. 



Of these characters the proportional size of the eye appears 

 to be the most reliable. Figs. 1 and 4 represent dorsal views 

 of the anterior portions of the Irish specimen of B. gracilis 

 and of a young male example of B. Payeri (36 mm.) in which 

 this distinction is clearly shown. 



Although the Irish example bears a distinct appendix mas- 

 culina on the inner branch of the second pair of pleopods, yet 

 the small size of the specimen as compared with Smith's ovi- 

 gerous females suggests that some of the features by which 

 this individual can be distinguished from B. Payeri may be 

 modified by further growth. Such are the concave external 

 border of the antennal scale, the rudimentary condition of the 

 finger-like process on the endopod of the first pair of pleopods 

 (fig. 2) and the straight-sided telson with long spines on its 

 rather broadly truncate apex (fig. 3). Smith figures the ex- 

 ternal margin of the antennal scales as straight in adult female 

 gracilis and, when detailing the dilferences between that 

 species and Payeri, makes no reference to the form of the 

 telson — a feature which could scarcely have escaped notice had 

 the distinctions been at all as great as is shown in figs. 3 and 

 6. 



Size. — As stated above, the Irish specimen measures 19 mm. 

 Smith's material consisted of two egg-laden females, one of 

 which was 39 mm. in length. Ovigerous females of B. Payeri 

 are usually found to have attained a length of 50 mm. or more. 



Colour in life. — When freshly caught the body of the Irish 

 specimen was perfectly clear and transparent, the red oral 

 and purplish hepatic regions showing distinctly through the 

 walls of the carapace. The sixth somite, telson and uropods 

 were pale rose red, as were also the antennae and antennules. 

 The eyes were brownish black, wdth a golden reflection. The' 

 third maxillipedes were red and all the pereiopods were very 

 faintly tinged with the same colour. 



