RECENT BRITISH OSTRACODA. 



431 



males, as has been showu to be the case in some Crustacea. A curious roughly punctate 

 and small form, which I suppose to be referable to a variety or stage of growth of this 

 species, is represented at Plate XXV. figs. 49, 50. 



2. Etjcttheee Aegus (G. O. Sars). (Plate XXVII. figs. 49-51.) 

 Cytheropsis Argus, Sars, loc. cit. p. 58. 



Scandinavian type (?). Distribution: Recent — Norway, Great Britain, and Ireland. Fossil — Glacial, 

 Scotland and Norway. 



Valves of the female, as seen from the side, subovate, highest in the middle ; height 

 equal to more than half the length. Anterior margin rounded, posterior rather narrower 

 and obliquely rounded ; superior margin highest in the middle, thence sloping with a 

 gentle curve towards each extremity, but more steeply backwards ; inferior slightly sinu- 

 ated in front of the middle. Outline, as seen from above, ovate, widest behind the middle, 

 greatest width equal to half the length ; obtusely pointed in front, rounded behind. 

 Shell pellucid, thickly set with rounded white papillae, which are very much larger than 

 those of the preceding species. " Second joint of the upper antennae about equal to the 

 united length of the following three, last joint short, ending in a strong spine and two 

 or three setse ; lower antennae short and thick, last joint larger than usual, and armed 

 with two claws, of which the internal is the smaller, the external strong and armed on 

 the anterior margin, towards the apex, with six teeth. Internal segment of the first 

 maxillae forming a simple spine. Peet very short, terminal claw scarcely longer than 

 the united length of the two last joints." 



Length -4-5- in. , ry <vv,.— 



Hab. In shell-sand, Galway Bay {Prof. Rowney) ; Girdler Sand {Mr. E. C. Davison) ; off Holy Island 

 (G. S. B.) ; Shetland {Mr. D. Robertson). 



My collection contains only two or three specimens (one a female, the others males) 

 from the three first-named localities ; but Mr. Robertson obtained a fine series from his 

 Shetland dredgings, off the Isle of Papa. 



Genus 5. Ilyobates, G. O. Sars. 



Valves thin and pellucid, subovate, truncate behind ; smooth and shining, and set with 

 very small distant papillae. Hinge-joint simple, formed by a slight projection of the 

 left valve, which is received into a corresponding depression of the right. Upper antennae 

 very stout, five-jointed, the first two joints much thickened, the last three short and 

 bearing long curved spines ; lower antennae four-jointed. Mandibles small, with unu- 

 sually long slender teeth; palp three-jointed, the second joint elongated, "branchial 

 appendage having two long ciliated setae and one rudimentary." Maxillae of the usual 

 form. Peet very short; the first two pairs three-jointed, the last pair four-jointed. 

 " Eight foot of the last pair, in the male, prehensile and only three-jointed, terminal claw 

 very large and strong. Abdomen of the female very convex above, the postabdominal 

 lobes bearing two short hairs." Eyes wanting. 



