176 SUPPLEMENT. 



bishire)!; Belfast, 106 ft. (Bryce and Hyndman). E. Atlantic 

 coasts of Prance and Spain. 



P. 180. A. NODULOSA. Orkneys ; a single valve (Thomas) ! ; 

 N. of Hebr., 170-530 f. (C. and T.) . P. Norway and Calabria ! 

 E. Loffoden L, 300 f. (Sars); Med. and Adr. ! A. scabra, 

 Poli, and A. aspersa, Philippi. 



P. 180. A. TETRAGONA. P. Portrush (A. Bell)!; Italy 

 (Scacchi and others). E. Madeira (Watson) ! 



P. 183. A. BAKBATA. E. Atlantic coasts of Prance, from 

 Quimper to Rochelle. 



P. 188. GALEOMMA TTJETONI. 



It has no pallial tube. The mantle is folded on both sides 

 in front, so as to form a rather wide incurrent opening, through 

 which food and aerated water are introduced. Innutritious 

 matter and perhaps the exhausted water are occasionally 

 ejected through this opening by a kind of spasmodic jerk. At 

 the opposite or posterior end there is a round hole in the 

 mantle, which has an excretal function; its margin is mi- 

 nutely scalloped. This latter orifice is sometimes closed. 

 Above each of these orifices is a remarkable short club-shaped 

 process, like a small tentacle; these processes are not protruded, 

 but are capable of a slight degree of extension. They may 

 serve as feelers or tentacles to warn the molluskof any enemy 

 approaching it from behind. The posterior process has the 

 end thicker than the anterior one ; otherwise they appear to 

 be equal in size. The mantle is spread outside over the shell, 

 so as to make the latter internal, as is partially the case in 

 Gyprcea. Its surface is covered with tubercles of different 

 sizes ; and around the edges of the valves on each side is a 

 row of 4 tubercles of a larger size than the rest, and resembling 

 eye-specks. I could not detect any " cord" or mark to sepa- 

 rate the outer and inner layers of the mantle ; the edges of the 

 valves showed the only line of division. The foot is tongue- 

 shaped, and extremely flexible. It is thrust out in front to a 

 considerable distance when the animal is on the march. The 

 valves then lie open with the beaks upwards. When the 

 Galeomma is at rest, it adheres by the inner and expanded 

 flaps of the mantle. The fascal pellets are oval and light yel- 

 lowish-brown. Clark has well described the byssus. The 

 substance of the body is gelatinous and almost transparent. 

 The gills and palps (2 pairs of each) are distinct ; the latter 

 are pale brown. 



