Mr. Jeffreys on British Mollusca. 41 



quadrato ; marginibus integris ; bysso ex filis perj)aucis curtis 

 crassiilis composito ; long. ^, lat. i unc. 



I have just received from Mr. Bean specimens of this pretty Httle 

 Modiola. He says they were taken from the stomach of a Sander- 

 Ung, which was shot on the north shore at Scarborough ; they were 

 mixed with the young of Mi/tilus edulis and Littorina liff oralis. I 

 regret that they reached me too late for illustration, my drawings 

 being at the time in the engraver's hands. It somewhat resembles 

 the fry of Crenella nigra, which is quite devoid of any longitudinal 

 ribs or strise ; but the latter are of an oblong shape, and flatter, and 

 they have no epidermis. M. agylutinans, or vestita, is also of a 

 different shape, and not so tumid as this, although its epidermis is 

 somewhat similar. 



I much doubt the propriety of separating Crenella from Modiola, 

 because the former is in its earliest stage of growth also quite smooth. 

 It is true that some of the Crenelles inhabit the tunic of Ascidians ; 

 but others (as C. costulata, rhonibea, and decussata, as well as C. 

 discors in its young state) are free. A few of the Modiolce (as M. 

 tulipa of British authors, and M. agglutinans) make and inhabit nests, 

 while the rest are free. But these habits are not uniform, nor in my 

 opinion sufficiently important in themselves to form a generic cha- 

 racter, Mr. Stimpson, in his recent memoir on the New England 

 shells, gives it as his opinion that Modiola, Modiolaria, and Crenella 

 ought to be reunited to Mijtilus, on the ground of the animals being 

 the same in all, and of the differences which exist in species of these 

 so-called genera being as great inter se as between the genera them- 

 selves. He also says that the British species of Crenella, which are 

 found on the North American coast, do not possess the habit of 

 burrowing in the tests of Ascidite. 



Crenella costulata, ii. 20.5. Herm (3/r. Macculloch). 



Nucula nitida, ii. 218. Dead valves are abundant in dredged sand 

 from the Turbot Bank, Belfast Bay. 



N. radiata, ii. 220. "Weymouth {Mr. Thompson). 



Area tetragona, ii. 234. Abundant in crevices of the slate rocks 

 at Bantry {I)r. Armstrong, Mr. Barlee, Rev. Mr. Norman, and 

 J. G. J.). 



Limopsis pellucida, n. s. PI. II. fig. 6 a-d. 

 Testa ovata, ventricosa, nitida, pellucida, glabra, vix subauriculata, 

 lineis incrementi conspicuis ; umbonibus rectis, prominulis, obtusis ; 

 margine integro ; cardiue foveola media triangulari, subtusque 

 denticulis 3 acutis, ad latus dextrum 1 1 et sinistrum 9 dentibus 

 falcatis, instructo ; ligamento foveolam cardinalem occupante ; 

 long- TO' lat. 3V unc. 



I found two perfect specimens and a single valve of this almost 

 microscopical shell in dredged sand from Guernsey ; and the dis- 

 covery is most interesting in adding a second species to the list of 

 recent Limopsides. It appears to be adult, as the teeth are fully 

 developed. It has no affinity with the fry of Pectunculus Glyci- 



