432 



MR. G. S. BRADY'S MONOGRAPH OF 



Ilyobates bartonensis (Jones). (Plate XXXIV. figs. 11-14, & Plate XL. fig. 5.) 



Cytherideis bartonensis, Jones, Tertiary Entomostraca, p. 50, pi. v. figs. 2a, 2b, 3a, Sb. 

 Ilyobates prcetexta, G. O. Sars, loc. cit. p. 60. ^ 



Scandinavian type. Distribution: Recent — Norway, Britain, Bay of Biscay. Fossil — Tertiary, England. 



Carapace of the female, seen from tlie side, elongate, subovate, slightly higher 

 behind than in front ; greatest height behind the middle and equal to half the length. 

 Anterior margin evenly rounded, posterior obliquely rounded, almost truncate. Superior 

 margin slightly arched, inferior nearly straight and forming almost a right angle with 

 the posterior extremity. Outline, as seen from above, ovate, tapering in front to an obtuse 

 point, posterior extremity truncate and evenly excavated; greatest width behind the 

 middle and equal to nearly half the length. End view subcircular. Carapace of the 

 male much narrower and more elongated. Shell smooth, pellucid, with opaque patches, 

 the brown body of the animal shining through ; surface set with small distant papiUae, 

 and, more especially along the anterior and inferior margins, with rather long single 

 hairs. Lucid spots large, quadrangular, four in a transverse row, mostly two or three 

 more in front, and others sometimes scattered irregularly over the valves. Last three 

 joints of the upper antennae shorter than the preceding one ; basal joint of the lower 

 antennae bearing on the upper margin a brush of long hairs ; last joint terminating in 

 three long, slender, nearly equal claws. Terminal claw of the second pair of feet 

 longer than that of the rest. " Basal portion of the copulative organs of the male very 

 large, subquadrangular, armed behind and below with a long spiniform process ; distal 

 portion short, acutely produced before and behind." 



Length in. 



Hah. The Dogger bank off Scarborough [Mr. Leckenby's dr edgings) ; the Minch, 45-60 fathoms, and 

 Loch Alsh'and Loch Eyne {Mr. J. G. Jeffreys) ; Shetland {Mr. D. Robertson). 



This is a very peculiar species, and cannot be confounded with any other recent form ; 

 but there is one which occurs in some of the older glacial clays which, if not identical 

 with the present, is at any rate very closely allied; it is, however, larger and less 

 elongated, besides presenting other minor differences. It is interesting to note that 

 this, and one or two other species occur (in Britain) only on the Dogger bank, and on 

 the western and northern shores of Scotland. 



Genus 6. LoxoconchA, G. 0. Sars. 



{Normania, Brady, Zool. Trans, vol. v.) 



Valves subrhomboidal in shape, mostly regularly convex ; surface usually marked with 

 fine concentric pittings and distant circular papillae, rarely bearing deep polygonal 

 excavations ; ventral margin forming a thin and prominent keel behind the middle ; 

 posterior dorsal angle obliquely truncate. Hinge-joint formed by four small teeth, 

 situated at the extremities of the hinge-line, two on each valve, the intervening portion 

 of the valve-margin often finely crenulated. Limbs of the animal slender and colourless. 

 Upper antennae very slender, six-jointed, the last joint very long, linear, and bearing 



