8 Gr. O. Sars. 



viewed dorsally, exhibits a broadly cordiform shape, its 

 greatest width occurring far behind the middle, and about 

 equalling the length. Anteriorly it gradually tapers, so that 

 the frontal margin ajDpears narrowly rounded; behind, it 

 appears abruptly constricted, with the terminal lobes closely 

 appressed to the body, and acutely produced, pointing straight 

 behind. The posterior sinus is moderately deep and evenly 

 rounded at the bottom, and its edges appear almost smooth, 

 the usual marginal denticles being obsolete. The cervical 

 sulcus, with its median protuberance indicating the mandibular 

 segment, is very conspicuous; the dorsal keel is also well 

 marked throughout the posterior part of the carapace. On 

 each side, and at some distance from this keel, a very distinct 

 sabre-like eminence is observed indicating the place where 

 the shell-glands occur imbedded between the two lamellæ 

 of the carapace. In no other species have I seen these 

 eminences so strongly marked. The whole surface of the 

 carapace is perfectly smooth and glossy, without any traces 

 of prickles or of any sculpture whatever. 



The eyes are rather large and less divergent behind 

 than in A. numidicus. The post-ocular tubercle is of moderate 

 size resembling in shape that of the above-named species. 



The exposed part of the body is very slender, cylindric, 

 though somewhat tapering distally. It exceeds the median 

 length of the carapace by almost i/s of its length, or, more 

 precisely, by its 7 posterior segments, and is accordingly 

 rather longer in proportion to the carapace than in the 

 female of A. numidicus. About 30 segments may be counted 

 in this part, the anterior 16 of which are provided with 

 legs, forming, as usual, two dense converging rows, which 

 partly project on each side, when the animal is viewed 

 dorsally (see fig. 1). The remaining 14 segments are without 



