233 



the form previously recorded as Bythocvthere simplex Norman, as the type of 

 a particular genus likewise included within the present subfamily. 



Gen. 45. Bythocythere, G. O. Sars, 1865. 



Generic Characters. Shell of somewhat varying shape, but as a rule rather 

 tumid, with more or less conspicuous lateral expansions and with the posterior 

 extremity obtusely produced. Valves comparatively thin, with the surface 

 smooth or faintly punctate; hinge imperfectly developed. Eyes in most cases 

 wanting. Anterior antennas with the segments of the basal part rather dilated, 

 the distal one obpyriform in shape and provided with 3 bristles, one on each 

 side and one rather smaller at the end; terminal part very narrow and flexible, 

 4-articulate, with the joints nearly equal in length and clothed with scattered 

 simple setae. Posterior antennae with the 1st joint of the terminal part rather 

 large, middle joint not subdivided and having the anterior setiferous ledge 

 close to the end, last joint armed with 3 claws successively increasing in length 

 posteriorly; flagellum with the knee above the middle. Mandibular palp with 

 the vibratory plate well developed, fringed with 6 8 plumose setae. Maxillae 

 with both the masticatory lobes and the palp short and stout, vibratory plate 

 comparatively large and provided at the base with 4 densely crowded deflexed 

 bristles. Legs slender and prolonged, seta at the base of the 1st pair replaced 

 by a small lamella divided at the end into 2 finely ciliated setiform lashes 

 and having moreover 2 simple bristles laterally; each of the 2 proximal joints 

 of the terminal part in all the pairs provided at the end anteriorly with a well 

 defined seta. Caudal lamellae somewhat deflexed and conically produced, with 

 one apical and 2 lateral bristles. Copulative appendages of male comparatively 

 small, with the terminal part well defined and abruptly deflexed. 



Remarks. This genus was established in the year 1865 by the present 

 author and has been admitted by all subsequent authors. It is here taken in 

 a somewhat more restricted sense than at first adopted, one of the species, 

 B. simplex Norman being, as mentioned above, discarded to form the type 

 of a particular genus, Macrocythere. 5 species referable to the present genus 

 will be described in the sequel. 



127. Bythocythere turgida, G. O. Sars. 



(PI. CVII). 

 Bythocythere turgida, G. O. Sars, Oversigt af Norges marine Ostracoder, p. 84. 



Specific Characters. Female. Shell very tumid, with the ventral face 

 flattened, seen laterally, short subrhomboid in shape, nearly equally high in 



29 Crustacea. 



