Rev. Canon A. M. Norman 07i Bathynectes. 273 



a Portunidan from the fishing-banks off the west of Norway, 

 where it was living in 100-200 fathoms, for which he estab- 

 lished the genus Thranites, which genus is undoubtedly 

 synonymous with the Bathynectes of Stimpson. The species 

 is also the same ; but I am of opinion that the crusta- 

 cean had long before been described by O. G. Costa in the 

 * Fauna del Kegno di Napoli/ in which work a fine plate 

 illustrates it. I will now proceed to describe the genus and 

 its representatives. 



Family Portunidae. 



Subfamily Pobtunin^. 



Genus Bathynectes, Stimpson, 1871, 

 = Thranitesj Bovallius, 1877. 



Stimpson's characters are as follows :■ — 



"Very near Portunus, but differing in its antero-lateral 

 teeth, which are not like those of a saw, but are somewhat 

 fipiniform and separated by considerable intervals. The front 

 also has no median tooth, and the hiatus of the orbit is widely 

 open, not being filled by the basal joint of the external 

 antenna?, which is narrow and firmly soldered anteriorly to 

 the process of the front. The meros joint of the external 

 maxillipeds is as broad as long, and does not project ante- 

 riorly, but fits accurately to the anterior edge of the buccal 

 area. The ambulatory feet are very slender; those of the 

 first pair much shorter than those of the second ; second and 

 third pairs very long, the third longest ; fourth pair two thirds 

 as long as the third." To tiiese characters may be added 

 that the ultimate joint of the fourth pair is flattened into a 

 swimming-blade, as in Portunus, and is not furnished with 

 any median rib. A transverse ridge crosses the carapace, 

 and unites the bases of the greatly developed posterior lateral 

 spines, which much exceed the preceding spines in size and 

 are sharply acute. 



In the adult of the typical species the frontal margin is 

 furnished with four teeth, so that, as Stimpson says, there is 

 no median tooth ; but in the young these teeth are much less 

 acute, and might be described as lobes, and the central pair 

 are united into one process, which is emarginate distally, this 

 emargination indicating the separation which afterwards takes 

 place in this process into two entirely distinct teeth. 



