434 



MR. G. S. BRADY'S MONOGRAPH OF 



margin. Apical portion of the male copulative organs tuberculated behind, acuminate 

 in front. Eyes distant and separate. 



Length ^ in. . c 2.6 <ri-^- 

 Hab. Littoral and in deep water. In shell-sand from the Girdler Sand (Thames), Cowes, Baltimore, 



and Donegal {Mr. E. C. Davison) ; Isle of Man, Cumbrae, Oban, Lerwick {Mr. D. Robertson) ; 



Guernsey, Falmouth, Swansea, Youghal, Skye, Stornoway, Tobermory {Rev. A. M. Norman) ; 



Arran, Roundstone, Galway, and South Wales in shell-sand ; Birterbuy and Roundstone Bays ; 



dredged, and in rock-pools, Arranmore and Sunderland {G. S. B.) ; Channel Islands and Hebrides 



{Mr. Jeffreys) ; Devonshire coast, 60 fathoms {Mr. Spence Bate) ; Norfolk coast {Mr.D. O. Drewett). 



Loxoconcha impressa is one of the commonest of British species, occurring almost all 

 round our shores, but much more sparingly on the eastern coast. Where it does occur, 

 however, it is usually, as in the west of Ireland, the Isle of Man, and the Pirth of Clyde, 

 one of the most abundant species. 



The surface-marking varies considerably. Young specimens are smooth, pellucid, 

 finely punctate, and beset with large circular papillae ; but as age advances the shell 

 becomes covered with a thick calcareous crust which obliterates the papillae, the puncta 

 becoming at the same time coarser and deeper. This state is represented at fig. 40, 

 where a portion of the outer crust {b) has been detached, exposing the original shell- 

 surface («). This is interesting as showing one possible source of error in the discrimi. 

 nation of species, many of which have been founded on characters not so distinct as 

 those shown in the two conditions of fig. 40. When I applied the name carinata to this 

 species I believed that Dr. Baird's Cythere impressa was the species here called, after 

 G. O. Sars, Cythere villosa. An examination of the type specimens and of the original 

 description, shows, however, that the term impressa refers to the present species. 



2. Loxoconcha granulata, Sars. (Plate XXV. figs. 51, 52.) 



Loxoconcha granulata, Sars, loc. cit. p. 64. 

 Distribution : Britain, Norway. 



Carapace of the female, seen from the side, subrhomboidal ; greatest height in the mid- 

 dle, and equal to more than half the length. Anterior margin obliquely rounded ; pos- 

 terior forming an obtuse projection in the middle, obliquely truncate above ; superior 

 margin very slightly arched, inferior convex, sinuated in front of the middle. Outline, as 

 seen from above, subovate ; greatest breadth in the middle, equal to half the length ; ex- 

 tremities equal, sharply tapering. The shell of the male is more elongated and straighter 

 on the superior margin, which is also more angular at the extremities. Surface of the 

 valves marked by small and closely set concentric pittings. " Second joint of the inferior 

 antennae shorter than the three following ; last two joints equal, elongated ; third joint 

 of the lower antenna almost as in L. tamarindus ; its anterior border bearing, above the 

 median setse, some equally distant very short hairs. Second joint of the last pair of 

 feet longer than the two following. Male copulative organs large, basal portion sub- 

 quadrangular, apical portion produced before and behind into a very slender subulate 

 process. Eyes separate." 



Length (male) in. 

 Hab. In oyster-ooze from Stranraer. 



