defined along the middle of the dorsal face, the 1st one very narrow, bandlike, 

 flanking the sides of the cephalon; the succeeding ones forming behind, to each 

 side, an obtuse prominence, and sending off laterally a narrow subcylindric prolon- 

 gation, carrying the corresponding leg. Metasome abruptly twisted to the left, 

 and gradually tapering distally, terminal piece pronouncedly clavate in form, and 

 exhibiting near the tip 2 small rounded tuberosities as the rudiments of the uro- 

 poda. Lamellae of pleopoda subequal, rounded oval in form. Body of young 

 female rather unlike that of the fully grown one, anterior division perfectly sym- 

 metrical and rather broad, flattened above, with the lateral edges of mesosome 

 forming a continuous line, slightly insinuated between each segment ; legs project- 

 ing laterally. Metasome turned more or less to the left, and somewhat shorter 

 than the preceding part of the body, pleopoda more regularly arranged. - - Body 

 of still younger female (1st postlarral stage) almost perfectly symmetrical through- 

 out, sub-pyriform in outline, anterior division rounded oval, with the dorsal 

 face convex, the ventral concave, cephalon freely projected in front, lateral edges 

 of mesosome curving below, legs folded in beneath the ventral face; metasome 

 extended nearly in the axis of the body, and having the inner lamella of the pleo- 

 poda rudimentary. Adult male narrow, sublinear, with the segments of meso- 

 some very sharply denned, their lateral parts being separated by deep incisions, 

 metasome forming an undivided, narrow, sub-cylindric piece. Colour of female 

 whitish. Length of fully grown female 11 mm., of male 3 mm. 



Remarks. This is the first recorded species, and may accordingly be 

 regarded as the type of the genus. It was described in the year 1843 by H. 

 Rathke as Phryxus paguri. The Bopyrus limlt/tnli of Kroyer, figured, but not 

 described, in Gaimard's work, seems to be an immature specimen of this spe- 

 cies, and this is also undoubtedly the case with Phryxus fnstiettudatus Sp. Bate 

 and Westwood. The Athelge fulludc of Hesse is regarded by Messrs. 8p. Bate 

 and Westwood as identical with Kathke's species, and I am also inclined to be- 

 lieve that the Prosthcte cannelee of the same author is nothing but an immature 

 specimen of this species. 



Occurrence. - Kathke found 3 specimens of this form off the west coast 

 of Norway (probably at Christiansund), on Eupagurus beri/linr<his. I have my- 

 self taken it from the same Crustacean at Molde, and moreover have had an 

 opportunity of examining a large number of specimens belonging to the Copen- 

 hagen Museum, and collected partly in the Kattegat, partly in the Skagerak. All these 

 specimens were likewise found clinging to the upper face of the metasome in as 

 many specimens of Eiqxn/nru.^ berult<ir<l/i. The parasite invariably turns its 

 head backwards in relation to its host, and its dorsal face to the skin of the 



