CETJSTA.CEA OF THE MEEGTJI AECHIPELAGO. 15 



distinguished by tLe longer spines of the rostrum, and from 

 Herbst's species moreover by the direction of these spines. 



The cephalothorax is subpyriform, triangular, much more nar- 

 rowed anteriorly than the cephalothorax of II . oryx, A. M.-Edw., 

 and even a little more than that of II. Pleione. In the largest 

 specimen (which I am describing) the proportion of the length* 

 of the cephalothorax to the distance between the external angles of 

 the orbits is as 9 to 4, whereas in S. Pleione it is as 5 to 2. In the 

 new species the proportion of the length of the cephalothorax to 

 the breadth (measured a little before the lateral epibranchial spines, 

 where the carapace is broadest) is as 15 to 13. The gastric and the 

 anterior cardiac regions are each elevated into a convex, rounded 

 tubercle, both of which are about equally prominent. Between 

 these two tubercles a small median transverse tubercle occurs 

 in S. Pleione, which is not found in this species. The posterior 

 cardiac region also rises into a small blunt median tubercle, 

 directed obliquely backwards, and on each side of it an elevated 

 line is observed running parallel with the posterior margin 

 of the cephalothorax. 



In H. migendorfi there is no median longitudinal vseries of 

 spines on the upper surface of the cephalothorax. In II. Pleione, 

 on the contrary, the posterior cardiac region rises into an 

 acute spine. Immediately behind the imaginary line which 

 unites the fissures of the supraorbital margins with one another, 

 in II. Pleione five small, blunt, semiglobular tubercles or spines 

 are found on the anterior declivity of the great gastric tubercle, 

 arranged in an arcuate line ; in our new species only the two 

 lateral tubercles of this group are found, while the three middle 

 ones are almost completely wanting. The epibranchial spine, 

 with which each side of the cephalothorax is armed behind the 

 middle of the lateral margins, in our species is comparatively 

 much stronger, acute, and curved upwards ; an imaginary line, 

 which unites the bases of the two epibranchial spines with one 

 another, crosses the posterior declivity of the anterior cardiac 

 region. Betv/een the anterior cardiac tubercle and the epi- 

 branchial spines two small, scarcely prominent, blunt tubercles 

 are found on each side of the former, lying in an oblique 

 direction; two imaginary lines, which unite the tubercles of 



* The length of the carapace is the distance between the posterior margin of 

 the cephalothorax and a transverse imaginary line, which unites the anterior 

 angles of the supraorbital margins. 



