476 



MR. G. S. BRADY'S MONOGRAPH OF 



Cytheropteron rectum, nov. sp. 



Carapace, as seen from the side, oblong, subquadrangular, nearly equal in height 

 throughout ; height equal to less than half the length ; extremities rounded ; superior 

 margin straight, terminating abruptly at each extremity in a small protuberance ; 

 inferior almost straight ; dorsal aspect oblong subovate, widest behind the middle, 

 suddenly constricted at the posterior third ; extremities pointed, width rather more 

 than the height. Shell-surface closely and minutely punctate; lateral ala not very 

 prominent, rounded oflP in front, abruptly angular behind. 



Length 5V in. 



One specimen only was dredged, by Mr. D. Robertson, in Lerwick Bay, Shetland, in a 

 depth of 12-14 fathoms. 



Note on Cythere Jonesii. 



In the Mediterranean, the Bay of Biscay, and on the western coast of Ireland, a form 

 which appears to me to be properly referable to this species, but at the same time 

 remarkalily different in some minor characters, is abundantly met with. The points in 

 which it differs are, the much greater delicacy and transparency of the shell, and the 

 greater length and slenderness of the entire spinous armature. In the position of the 

 spines and the general outline of the shell, it does not differ appreciably from the typical 

 form of the species. I have no hesitation in identifying it with the Cytliereis cerato'ptera 

 of Bosquet, and, I think, also with the 6'. mhcoronata of Speyer. The figures given by 

 the latter author seem, indeed, to be widely different, but a specimen which he kindly 

 communicated to me is either identical, or very nearly so, with the form here noticed. 



