152 



were all provided with strongly marked lateral protuberances, whereas those 

 found at Tj0t0 were mostly missing such protuberances, and thus agreeing with 

 the form recorded by Dahl under the name of L. incisa. On a closer examina- 

 tion of the specimens collected in the latter locality I have found in some of 

 them distinct traces of protuberances in the same places as in the typical form, 

 and as no other differences could be detected between the 2 forms, I am now 

 of opinion that they should be combined in one species. All the specimens 

 observed were of the female sex. 



Distribution. Sweden, British Isles, Baltic, Germany, Switzerland. 



Fossil. Sweden, Scotland. 



Subfam. 2. Cytherideinae. 



Characters of the subfamily. Shell, as a rule of firm consistency, more 

 or less calcareous, with the surface generally distinctly sculptured. Hinge more 

 perfect than in the Limnocytherince, though wanting distinct closing teeth in 

 front and behind. Eye distinctly divided, in some eases absent. Antennae 

 built on the same type as in the preceding subfamily. Mandibular palp more 

 slender, with the first 2 joints confluent, vibratory plate less perfectly developed. 

 Legs successively increasing in length, with only a single seta on the anterior 

 border of the basal part, being, as a rule, conspicuously transformed in male. 

 Caudal rami extremely small, and imperfectly defined at the base. 



Remarks. This subfamily is established to comprise the genus Cytheridea 

 Bosquet and allied forms, which seem to me to present some particular charac- 

 ters distinguishing them both from the Limnicytherince and from the next sub- 

 family, Cytherince. 4 genera referable to this subfamily will be treated of in 

 the sequel. 



Gen. 31. Cytherissa, G. O. Sars, n. 

 Syn: Chyteridea (p.irt). 





Generic Characters. Shell club-shaped, very solid, with the surface 

 roughly sculptured. Valves subequal, with the marginal zone thickened and 

 the inner duplicatures narrow. Hinge showing slight traces of closing teeth 

 in front and behind, but without any crenulation of the edges. Eyes well 

 defined, though rather approximate. Antennae powerfully developed; the an- 

 terior ones with the terminal part 3-articulate and armed in front with 3 claw- 



