232 



BRITISH MOLLUSKS. 



In the neighbourhood of Belfast, writes Mr. Thompson, Pisidium 

 nitidum is found on Utricularia vulgaris growing in stagnant pools 

 excavated in brickniaking. 



5. Pisidium Casertanum. Caserta Pisidium. 



Shell ; somewhat triangularly orbicular, rather compressed, dull 

 ash-horny, concentrically finely striated, very 

 inequilateral, anterior side obliquely slopingly 

 produced, posterior abruptly truncate ; umboes 

 rather obtuse. 

 Cardium Casertanum, Poli (1791), Test. utr. Sicil. vol. i. p. 



65. pi. xvi. f. 1. 

 Pisidium cinereum, Alder (1833), Cat. Moll. Northumo. 



Supp. p. 4. 

 Pisidium australe, Philippi (1836), ~Enum. Moll. Sicil. vol. i. 



p. 39. 

 Ci/clas lenticularis, Norinand (1844), Not. Nouv. Cycl. p. 8. 



f. 7, 8. 

 Pisidium tliermale, Dupuy (1849), Cat. Extram. Test. no. 238. 

 Pisidium lenticulare, Dupuy (1852), Hist. Moll. vol. vi. p. 681. pi. xxx. f. 2. 

 Pisidium Casertanum, Bourguignat (1853), Voy. Mer Morte, Moll. p. 80. 

 Sab. Central and Southern Europe. Syria. Throughout Britain. (In 

 ponds and gently flowing streams.) 

 This species is the original Cardium Casertanum of Poli, 

 described by the celebrated Neapolitan naturalist towards the close 

 of the last century, from a specimen collected in the great aque- 

 duct of Caserta. Excepting P. amnicum, it is the largest of the 

 genus, rather compressed, finely striated, and of a dull ash-horny 

 aspect. MM. Moquin-Tandon and Baudon refer to P. Casertanum, 

 the small P. pulchellum of Jenyns. Forbes and Hanley believe 

 this to be distinct, and half-a-dozen species, as will be seen by our 

 list of synonyms, have been made of it by some authors. M. Mo- 

 quin-Tandon remarks that of all the Pisidia this species varies the 

 most, according to localities. P. Baudonianum and rotundatum of 

 Cessac, and P. sinuatum of Gassies, he thinks may prove to be 

 merely abnormal forms of it. 



I cannot find any evidence of P. Casertanum ranging to the 

 northern parts of Europe. It appears in Syria. 



