210 



Remarks. — The present genus is very different from any of the pre- 

 ceding ones, whereas it exhibits some points of affinity to the next genus ; and 

 indeed Rathke combined them in his genus Phryxus. It is now, however, gene- 

 rally acknowledged that the genus of Rathke comprises 2 distinct generic types, 

 and the name Phryxus should accordingly be restricted to one of these types 

 only, whereas for the other type, the one here treated of, the name Athelges, 

 proposed by Hesse, ought to be retained. The peculiar contortion of the body 

 in fully grown female specimens has not yet been sufficiently recognized; for the 

 species have generally been described as perfectly symmetrical or nearly so, an 

 appearance which is only exhibited by immature specimens. Both in these 

 and in fully grown specimens, the metasom'e exhibits several very peculiar 

 features not found in any of the preceding genera. Firstly, it apparently con- 

 sists of only 5 segments, the last of which has the form of a cylindric or clavi- 

 form piece ; secondly, there is no trace of epimeral plates; and thirdly, the pleo- 

 poda, of which there are only 4 pairs, are extended laterally, and each 

 consist of a narrow stalk, to which are attached 2 lamellae of pronouncedly 

 branchial structure. The place where the parasite clings to its host, is also very 

 different from that in the preceding genera. The type of the genus is A. 

 paguri Rathke, to be described below. Mr. Hesse has also described several 

 species from the French coast; but to judge from his figures, only young speci- 

 mens seem to have come under his notice. One of these is regarded as the type 

 of a separate genus (Prosthete). 



l. Athelges paguri, Rathke. 



(PL LXXXVIII). 



Phryxus paguri, H. Rathke, Beitrage ziir Fauna Norwegens, in Nova Acta Acad Nat. 

 Curios. Vol. XX, p. 57, PI. 1, figs. 13—15, PI. 2, figs. 11, 12. 



Syn. : Bopyrus bernhardi, Kroyer (young). 

 „ Atlielge fullode, Hesse. 

 „ Prosthete cannel^e, Hesse (young). 

 „ Phryxus fusticaudatus, Sp. Bate (young). 



Specific Characters. — Body in fully grown females very asymmetrical, 

 twisted to one (generally the left) side, and at the same time exhibiting a rather 

 strong dorsal curvature; anterior division oblong, almost semicylindric, with the 

 dorsal face concave, the ventral one strongly vaulted. Cephalon oval quadran- 

 gular, only visible in a dorsal view of the animal. Segments of mesosome well 



