209 



not yet stated. Length of adult female scarcely exceeding 4 mm. ; that of 

 male 1 mm. 



Remarks. This form is evidently distinct from either of the 2 pre- 

 ceding species, differing, as it does, pronouncedly in both sexes. The specific 

 name here proposed refers to the poor development of the pleopoda and uropoda. 

 The latter appendages especially are very small as compared with those in the 

 2 preceding species. 



Occurrence. I have found this form occasionally in the branchial ca- 

 vity of Galathea intermedia Lilljeborg, taken off the south coast of Norway. 

 The parasite, when fully grown, causes a very strong and conspicuous tuberosity 

 on one side of the carapace of the Galathea (see fig. 2 *). I have also re- 

 ceived the same form from the Copenhagen Museum, likewise infesting that 

 species of Galathea. 



Distribution. Kattegat. (Copenhagen Mus.). 



Gen. 5. AthelgeS, Hesse, 1861. 



Phryxus, Rathke (part). 



Generic Characters. Body of fully grown female very asymmetrical, 

 twisted both dorsally and to one (generally the left) side ; body in younger sta- 

 ges of a rather different appearance, being more symmetrical and of a more or 

 less pronouncedly club-shaped form. Cephalon small, and withdrawn far 

 into the mesosome, being only visible in a dorsal view of the animal. Seg- 

 ments of mesosome in fully grown females distinctly defined only along the middle 

 of the dorsal face, lateral parts unconnected, narrow, undivided, coxal plates 

 very small. Metasome abruptly narrowed, without any epimeral plates, the last 

 2 segments united to a narrow, more or less claviform piece. Antenna? very 

 small, issuing close together from the extremity of the head. Maxillipeds with- 

 out any terminal joint. Legs rather robust, and in fully grown specimens pushed 

 wholly on to the dorsa face of the animal. Incubatory lamellae exceedingly large, 

 overlapping each other ventrally, the anterior ones produced in front far beyond 

 the cephalon, and folded in a funnel-shaped manner. Of pleopoda only 4 pairs 

 present, extended laterally, and each consisting of a narrow stalk and 2 lamella 

 of pronouncedly branchial structure. Uropoda only present as 2 wart-like tu- 

 bercles. Male of normal appearance, having the segments of metasome coalesced. 

 Parasitic on Pagurids, and always found clinging to the upper face of their 

 soft metasome. 



27. Crustacea. 



