210 DR. G. S. BRADY ON T THE [Feb. 1, 



Genus Siphlocandona *, gen. n. 



Shell elongated, elliptical, thin and fragile. Posterior legs 

 almost obsolete, their place being taken by an jll-developed club- 

 shaped appendage. Caudal rami of the usual form, armed 

 with two terminal claws and a very small marginal seta situated 

 almost close to the distal extremity : of the two claws that 

 situated above (or nearer the dorsal surface) is much the larger 

 of the two. In other respects like Candona. 



Siphlocandona similis Baird. (Plate XXVII. figs. 1-9.) 



1845. Candona similis Baird, (7) p. 162, pi. xix. figs. 2, 

 2a (1850) ; Trans. Berw. Nat. Club, ii. p. 153 (1845); 

 Ann. & Mag. Nat. Hist. xvii. p. 415, pi. ix. fig. 4. 



Female. — Shell, seen laterally, elongated, subelliptical, rather 

 higher in front than behind (fig. 1), length equal to more than 

 twice the height ; extremities well rounded, the anterior the 

 broader of the two ; dorsal margin quite straight, ventral gently 

 sinuated in the middle : seen from above (fig. 2) the outline is 

 elongate-ovate, widest in the middle, nearly twice as long as 

 broad, lateral margins evenly arcuate and tapering equally to the 

 extremities which are sharply pointed. Shell very thin and fragile 

 and showing no trace of sculpture; almost colourless. Valves 

 equal, their margins scarcely at all inflexed. Length 0-98 mm. 



Anterior antennae six-jointed, slender, their terminal setae long 

 and slender ; posterior antenna? four- join ted, moderately stout 

 \ug. 3) ; mandibles (fig. 4) bearing a stout four-jointed palp the 

 first joint of which is provided with a 4-setose branchial plate ; 

 first and second pairs of maxilla? of the usual form (figs. 5, 6) ; 

 feet of the first pair (fig. 7) four-jointed, inner margin of the 

 second joint rather densely setose, last joint bearing two very 

 unequally sized claws and a short seta : the homologue of the last 

 limb is a short, slightly curved, club-shaped process with a small 

 proboscidiform apex (fig. 8). Caudal rami simple, straight, 

 with smooth, non-setose margins, bearing two terminal claws, the 

 uppermost quite twice as long as the lower ; marginal seta very 

 small and situated almost close to the apical claw (fig. 9). Male 

 unknown. 



This species, which, though collected in 1897, has remained 

 unrecognized until now, is, I have little doubt, identical with that 

 described long ago by Dr. Baird under the name of Candona 

 similis, his description and figures agreeing in every particular 

 with my specimens. These, of which I took only a very small 

 number — some three or four — are from "the Mere" at Scar- 

 borough, a small sheet of fresh water lying under Oliver's Mount, 

 and I have more recently received specimens from Mr. Robert 

 Gurney, taken in Catfield Pen, Norfolk. 



The characters which essentially distinguish this genus from 



* crt^Xos, n cripple. 



