:; 



MR 



MONOGRAPH OF 



from above, ovate, widest in the middle ; greatest width equal to more than one-third of 

 the length. Shell smooth, pellucid, yellowish. Animal unknown. 



length 



i 



.> j 



IN. 



Hah. Birterbuy Hay, 10 fathoms (G. S. B.). 



Several examples of this species occurred in my dredgings ; but, owing to their having 

 been dried slowly with the mud in which they were taken, all trace of the animal 

 structure has disappeared ; and I can therefore only conjecture that they possibly belong 

 to the genus JPontocypris* . 



Genus 7. Bairdia, M'Coy. 

 Valves unequal in size, the left being considerably the larger and overlapping the right 



the dorsal and ventral surfaces. Surface of the shell smooth or 



iy 



as seen from the side, mostly obliquely subquadrate. Animal imperfectly 

 Post abdominal rami well developed, with long and slender terminal claws ; 



mar 



both on 

 Cara pace 

 known. 



gimil setae long and crowded together near the apex. 



Though examples of this genus are not particularly uncommon, I have only in one 

 instance succeeded in finding a carapace containing the animal ; and even this was so 

 imperfect as to prevent my obtaining accurate information as to its structure. Such of the 

 limbs as I was able to draw are figured in PL XXXVIII. ; but I cannot name them with 

 absolute certainty. The size of the various species would make it a very easy matter to 

 determine their structural characters if they could be procured in a living state. The 

 specimens in my collection have all been picked from masses of dried mud or sand ; and 

 in such cases it is seldom that the soft parts remain intact. The formation of the abdo- 



minal 



howe\ 



bt, shows distinctly that this genus must be classed amongst the 

 Cypridse ; and, from the characters of the shell, I conclude that it is, in all probability, 

 clo !y related to the following genus, Macrocypris. 



The British species are four in number, and are exclusively inhabitants of moderately 

 deep water t, ranging, in the British seas, from 10 to 60 fathoms. 



The numerous fossil forms described under the generic name Bairdia seem to be refer- 

 ible to many distinct genera. 



1. Bairdia inflata (Norman). (Plate XXVII. figs. 9-17, & Plate XXXVIII. fig. 5 



Cythere inflata, Norman, Ann. & Mag. Nat. Hist. vol. ix. p. 49, pi. iii. fisrs. 6-8. 



a, Brit. Mas. Cat. Brit. Crust, p. 108 {fide Norman). 

 subdeltoidea, A. White, Pop. Hist. Brit. Crust, p. 293 : narrow var 



Formation 

 Atlantic type. Distribution : Recent 



Entom. Cretaceous 



Britain 



Fossil — Raised beaches, Scotland. 



Shell tumid ; as seen from the side subrhomboidal in outline, highest near the middle 



Since this was written the specimens on which the genus Aglaia is founded have come into my hands ; and it is 

 more than probable that the present species will prove to be referable to the same genus 



indeed Z^ hT "J* "^ " "^ T "^ * <** ^ **»"« ™* ** British Islands, which are, 

 ^TJ^ZZ™:^ th ° Se ^ ** ^ ^ <*~ — • °* -en on such coasts as that of Norwa, 



quoted 



