Caudal rami scarcely longer than that segment, and not at all divergent; seta 

 oi outer edge attached about in the middle; apical setae comparatively short. 

 Anterior antennae about the length of the cephalon and rather narrow, being 

 clothed with comparatively short anteriorly-curving setae. Posterior antennae 

 unusually slender and attenuated, almost nacked, except at the tip, which 

 carries 3 strongly curved claws accompanied outside with 2 setae. Posterior 

 maxillipeds without any armature whatever, terminal joint small, tuberculiform. 

 Natatory legs well developed, with the rami subequal in length; inner ramus 

 of 4th pair fully as large as that of the preceeding pairs, but only provided 

 with 2 setae and 2 spines, the latter attached to the end of the terminal joint. 

 Last pair of legs with the free joint rather small, sub-cylindrical in form, and 

 carrying on the tip 2 very unequal setae, the inner one much the larger and 

 curved backwards. Ovisacs comparatively large, oblong in form, and only 

 slightly divergent. 



Male much smaller than female, and having the anterior division of 

 the body less expanded. Genital segment greatly tumefied. Posterior max- 

 illipeds powerfully developed, with the apical claw very long and slender. 



Body of female semipellucid, with the ovarial tubes of a bright rosy 

 colour; ova in the ovisacs reddish orange. 



Length of adult female 1.40 mm., of male 1.00 mm. 



Remarks. This form was first described by Aurivillius, and has sub- 

 sequently been recorded by several other authors. It is the type of the 

 present genus. 



Occurrence. I have found this form not unfrequently within the pallial 

 cavity of large specimens of Modiola modiolns taken in the outer part of the 

 Christiania Fjord, at Hvalor. Aurivillius has also occasionally obtained it from 

 My til us ednlis. 



Distribution. Bohuslan (Aurivillius), British Isles (Scott), coast of France 

 (Canu), Mediterranean (Raf. Monticelli). 



Gen. 42. HermanneNa, Canu, 1891. 



Generic Characters. Body of somewhat different form in the different 

 species, and having the integuments well chitinised, cephalon more or less 

 distinctly defined from the 1st pedigerous segment, and produced in front to 

 a well-marked incurved rostrum. Tail attenuated, with the genital segment in 



