52 



Praniza might be the female of Anceus. Indeed, the 3 forms are so widely diffe- 

 rent both in their general appearance, and in the structure of some of the appen- 

 dages, that one. may be easily led to suppose that they belonged to as many distinct 

 genera. The communications of M. Hesse therefore at first occasioned no little 

 discussion among Corcinologists, and the correctness of his observations relating 

 to the transformation of Praniza into Anceus, was even simply denied 1 ); but 

 subsequent investigations have, on the whole, fully confirmed his statements about 

 the peculiar trimorphism occurring in this genus. A rather large number of 

 species, amounting to more than 20 in all, have been recorded from different parts 

 of the Oceans; but the far greater part of them have been only described from 

 male specimens. To the fauna of Norway belong 4 species, to be described below. 



1. Gnathia maxillaris (Mont.). 



(PI. XXI, PI. XXII, fig. 1.) 



Cancer maxillaris, Montague, Trans. Linn. Soc, Tol. VII, p. 65, PI. 6, fig. 2. 



Syn: Anceus maxillaris, Lamk. cf. 



„ Praniza coerukata, Desm. (Larva). 



„ Anceus oxyuranis, Lilljeb. cf. 



„ Praniza Edwardii, Sp. Bate 9- 



„ ? Anceus manticorus, Hesse. 



Specific Characters. — Male. Body almost clavate in shape, being gradually 

 expanded in front, with the anterior part of mesosome divided from the posterior 

 by a rather deep constriction. Cephalosome transversely quadrate, deeply ex- 

 cavated above in its anterior part, dorsal face smooth and distinctly areolated, supra- 

 ocular denticle comparatively small. Posterior division of mesosome narrower 

 than the anterior, dorsal face quite smooth, without any areolation. Eyes well 

 developed. Mandibles rather large, broadly lanceolate, with a slight obtuse notch 

 outside, inner edge bulging in the middle, and obscurely crenulated in its outer 

 part, tip scarcely incurved. Pereiopoda with scattered tubercles inside the outer 

 joints. Pleopoda well developed, natatory. Uropoda with the rami foliaceous, 

 and fringed with long ciliated setaa. Terminal segment of metasome triangular, 

 gradually tapering to a point carrying 2 slender bristles. Sexual tubercle small, 

 but little prominent. Colour yellowish brown, with the areola? of the head whitish, 

 defined by narrow dark brown grooves. — Female: Body oblong fusiform, with the 2 



] ) It may be noted that the strange controversy which at first took place between 

 M. Hesse and Mr. Sp. Bate, was merely due to the fact that the latter author regarded the 

 adult female as a Praniza, whereas M. Hesse more correctly named it a female Anceus, 



