TRTTIA. 



59 



bpino; betrayed by a little hillock. It also gets into lobster-pots 

 for the sake of the bait. Bouchard-Chantereanx attributes to this 

 as well as to other whelks, the habit of piercino- and devouring bi- 

 valves. According to M. Lespe's, N. refirtilafc is preyed upon l)y n 

 parnsitio Trematode (Cercan'a mgi(tata) which infests its liver. 

 Its spnwn cases are deposited on the leaves of Zoatern nnd on 

 various other thinsfs Avhieh are left dry only at si)ring tides ; the 

 capsules are arranged in rows, and so closely tlmt they overlie 

 each other "like the brass scales of the cheek-band of n hussar'' 

 (Johnston). They are compressed pouches, eacli of the size of 

 a larofe spanole, su))ported on n very short stalk, with n small 

 opening at the top to idlow tlie fry to escape. Mr. Peach des- 

 cribed and figured the capsules in the Reports of two Cornish 

 Societies for 184.3 and 1844 ; and he has given us some amusing 

 particulars of the fry. These behaved themselves like the fry 

 of other gastropods, skipping about and whirling round by 

 means of their ciliated lobes, apparently in a state of pleasura- 

 ble excitement ; but it seems that the exercise was compulsory, 

 or necessary to prevent the attacks «f a swarm of infusoria, 

 which made short work of any tired or feeble infant Nanna. 



Mr. Jeffreys has named N. nifida (tig. 340) a shell which he 

 says is as distinct from N. reticulata as N. pt/gmaea is from N. 

 incrassata, and he states that he has not seen any intermediate 

 forms. He states that nitida is found only in brackish water 

 and on muddy bottoms. A specimen among a number dredged 

 by him in Roach River, had two e3-es on the right hand tentacle; 

 the eyes were smaller than usual, and close together. I agree 

 with Morch and Von Martens that nitida is mereh' a variety of 

 N. reticulata. Mr. Jeflfreys cites A', reticulata from Japan;* the 

 identity of the Japanese shell must be supposed to be in the 

 sense in which Mr. Marrat would regard it — yet I can admit it 

 also, if it be considered necessary to prove an immense distri- 

 bution for the species. N. reticulata, figured by Quo}' and 

 Uaimard in the A'oy. of the Astrolabe, is no', this species how- 

 ever, but jDrobably N. cremata, var. margaritifera. A curious, 

 thin, swollen form fron^ the Baltic is known as A^. cancellata, 

 Chemn (figs. 343-345). 



.Tour. Linn. Soc, xii, lOT. 



