60 HETEROPHROSYNID^E. 



seaweeds, at low-water mark and a little beyond it, on 

 many parts of our coast from Shetland to the Channel 

 Isles inclusive. It was first noticed near Dublin and 

 at Cullercoats by Mr. Alder. The only foreign localities 

 of which I am aware are Cape Levi near Cherbourg 

 (Mace), and Spezzia (J. G. J.). 



At the Whalsey Skerries J. diaphana occurs in com- 

 pany with its two congeners, /. globularis and J. opalina : 

 the scale of their comparative frequency is the order 

 here given, the last-named being the most numerous 

 of the three. The present species is very active in 

 crawling and floating ; and it spins a slimy suspensile 

 thread. When many specimens are left for some hours 

 in a vessel of water, they congregate in small clusters, as 

 if actuated by a social instinct. The spawn deposited 

 by one individual consisted of only two ova, which were 

 enclosed in a gelatinous hemispherical case. Owing to 

 the extreme and glassy transparency of the shell, the 

 dark reddish-brown liver is very conspicuous, even after 

 the animal has dried up. 



Perhaps this shell was the Turbo nitidus of Adams, 

 from the Pembrokeshire coast, where it is not uncommon. 



t>l -t>9 2. J. OPA'LINA*, Jeffreys. N a , JU 



Rissoa (?) opalina, Jeffr. in Ann. & Mag. N. H. ser. 2. ii. p. 351. J. opa- 

 lina, F. & H. iii. p. 154, pi. Ixxvi. f. 3, 4; iv. (app.) p. 267, pi. cxxxiii. 

 f. 6, and (animal) pi. MM. f. 2, a-b. 



BODY, above, dark- grey, mottled with purplish -brown or soot- 

 colour ; below, dirty yellow : snout short, rounded, seldom pro- 

 jecting beyond the foot ; front edge finely scalloped : tentacles 

 club-shaped, and of a paler colour [" very moderately setose," 

 Clark] ; they appear four in number, arranged in two pairs, 

 each tentacle being nearly equal in length and thickness ; the 

 second or lower pair are scarcely part of the snout, because 

 they issue from the neck, like the other pair : eyes sessile, rather 



* Of an opal hue. 



