RECENT BRITISH OSTRACODA. 



389 



greatest height equal to half the length. Anterior margin flattened, waved, running 

 obliquely upwards and forwards, and bordered, in many cases, by a flattened spinous 

 lamina (figs. 14-17). Dorsal margin forming a flattened arch, truncate in the middle; 

 ventral straight or slightly waved, bulging into a protuberant angle at its junction with 

 the anterior margin. Posterior margin narrow, rounded, or almost angular, and fre- 

 quently encircled by a narrow squamous lamina, which is irregularly dentated or spinous 

 (figs. 13-17). Outline as seen from above tumid, oval; greatest width in the middle, 

 equal to rather less than half the length; extremities obtusely pointed; line of junction 

 of the valves waved ; on the ventral margin the left valve much overlaps the right. 

 End view subtriangular, broad and rounded below ; width and height nearly equal. 

 Surface smooth and polished, or finely punctate ; pearl-white or cream-coloured. The 

 anterior extremity of the carapace bears sometimes, in old and well-grown specimens, 

 a number of short pointed tubercles, and is occasionally, as also the hinder extremity, 

 beset with coarse brown hairs (fig. 13). Lucid spots six to nine, arranged in a rosette. 

 Postabdominal rami terminating in two slender curved claws ; the internal very long 

 and finely tapered, considerably exceeding in length the ramus itself; the external 

 more slender and about half as long : on the internal border of the ramus, and very near 

 its apex, are five slender setse ; the upper two very short, the rest about equal in length 

 to the shorter claw. 



Length in., height -5-0 in. . & < ..n^...^. 



Hab. Lamlash Bay {Rev. A. M. Norman) ; Channel Islands, 15-30 fath.. Loch Alsli and the Minch 

 {Mr. Jeffreys's dredgings) ; Shetland {Mr. D. Robertson), off Hoy Head {Mr. D. O. Drewett) ; Devon- 

 shire coast, 60 fath. [Mr. Spence Bate's dredgings) ; in shell-sand from Arran and Galway Bay {Prof. 

 Rowney), and from Boundstone {Dr. Alcock) ; dredged in Poolvash Bay, Isle of Man, 12-15 fath., 

 and in Birterbuy Bay, 10-15 fath. (G. S. B.). 



This very interesting form was first described as a distinct species by the Rev. A. M. 

 Norman, under the name of Cy there infiata. Mr. Norman's specimens were taken from 

 shell-sand dredged in Lamlash Bay, from which locality Prof. T. Rupert Jones had also 

 previously obtained the species, considering it a variety of Bairdia subdeltoidea. Its 

 characters are, however, very distinct and constant ; and although some forms of B. sub- 

 deltoidea approach it very closely, I agree with Mr. Norman in the opinion that it should 

 be regarded as a distinct species. The typical form of B. subdeltoidea, has not, so far as 

 I know, been met with, in a recent state, in the British seas. A few specimens of it 

 occur in Mr. Jeffreys's Channel-Island dredgings, but they have the appearance of fossil 

 shells ; and as several Poraminifera dredged in the same place are evidently derived from 

 some submarine fossiliferous bed, the most reasonable inference is that the Bairdice were 

 likewise derived from the same source. One very fine specimen of B. injlata occurred 

 in the same dredgings, and is abundantly distinct from the fossil forms with which it 

 was associated. 



Bairdia infiata is tolerably abundant in Galway Bay and the neighbouring seas, but 

 appears to decrease rapidly in numbers to the east. On the eastern shores of Britain I 

 have no record of its occurrence. 



