RECENT BRITISH OSTRACODA. 



369 



As Eischer has identified Miiller's C. strigata with a species which seems to be very 

 different from the present, I have thought it best to describe our British species under a 

 new name. 



** Second foot without a claw, terminating in three moderately long and nearly equal seta. 



12. CrPEis GiBBA, Eamdohr. (Plate XXIY. figs. 47-54, and Plate XXXVI. fig. 2.) 



Cypris gibba, Ramdohr, Magaz. d. Gesellsch. naturforsch. Freunde zu Berlin, 1808, ii. p. 91, t. iii. 

 figs. 13-17 {fide Jones) ; Jones, Tertiary Entom. p. 15, pi. i. figs. 3fl-/, and woodcut, fig. 1, p. 16. 



Valves oblong, oval, nearly equal in height throughout, marked generally, but not 

 always, by two deep transverse sulci extending from the anterior half of the dorsum to 

 the middle of the valve. Extremities well rounded and nearly equal, fringed with hairs. 

 Dorsal margin straight ; ventral deeply sinuate in the middle. Seen from above, the 

 carapace is oblong-ovate, narrowed in front and rounded behind, marked on the anterior 

 half by one or more deep transverse sulci. End view subquadrate, keeled. Surface of 

 the shell deeply and coarsely punctate (fig. 51), cream-coloured or light brown, sometimes 

 nearly white. The shell is much thicker and stronger than that of any other Cypris 

 with which I am acquainted. The second foot bears at the apex of the terminal joint 

 three long setse, two of which are nearly equal in length, the other considerably shorter : 

 the penultimate joint has also two long and equal setae springing from its inner margin ; 

 and another, somewhat shorter, rises from the apex of the second joint. Postabdominal 

 rami flexuous, ending in two long and equal claws, and one very short seta ; the marginal 

 seta is unusually long, and is attached somewhat below the middle of the ramus. Eye 

 very black and conspicuous. 



Length in., height in. - *^ V \ .\. i i^-fv^vvA - 



Cypris gibha seems to be an almost ubiquitous species, but is liable to escape obser- 

 vation, owing to its habit of creeping on the bottom or imbedding itself in the mud or 

 soft clay. It is nevertheless a true Cypris, the lower antennae bearing a tuft of long 

 setae, and the second pair of jaws a branchial appendage. The armature of the second 

 pair of feet is peculiar, and the shell-structure very difierent from that usually seen in 

 this genus. The markings of the surface are very variable, some specimens being alto- 

 gether devoid of grooving or tuberculation, while others are deeply uni-, hi-, or trisulcate. 

 These variations do not seem to depend entirely upon age, though in young specimens 

 the sulci and tubercles are, as a general rule, feebly developed or absent. 



h. SetcB of lower antennae scarcely plumose, very short, not reaching to the apex of the terminal claws. 



13. Cypuis trigonella, n. sp. (Plate XXV. figs. 41-44.) 



Valves elongated, subtriangular, highest in the middle ; height equal to more than 



aperturam sublinearis ; valvulse convexiusculse, fuscse, fasciis tribus albis, postica nempe lunata, media obliqua, antica 

 arcuata ; vel, si mavis, valvulse albse, margine dorsali cingulo fusco cinctse, disco maculis duabus obliquis fuscis." 

 VOL. XXVI. 3 E 



