CHASTER AND HEATHCOTF. : MOLLUSCA OF OBAN. 307 



P. similis, Lask. Not uncommon off I.ismore and Maiden 



Islands. The specimens are beautifully rayed and mottled. 

 Mytilus eclulis, I>. Attached to rocks and stones on the 



shore. Small examples of the van gallop70vincialis^ Lam. 



occurred wedged in the crevices of the rocks. 

 Modiola modiolus, L. {Mytilus viodiohis). Dredged in 



Kerrera Sound, and found under stones at low water on 



Fraoich Island. 

 M. phaseolina, Phil. A few valves and immature living 



specimens dredged off Maiden Island. In the Sound of 



Mull, off ]>ismore lighthouse, the dredge brought up a large 



number of valves and several fine living specimens. These 



were unfortunately lost. 

 Modiolaria marmorata, Forb. A large number, some 



measuring 20 mm., were taken from the tests of Ascidians 



{Asa'dia mentula and others). Near Maiden Island these 



tunicates were crowded with Modiolarice^ Mr. Standen 



being often kept fully occupied in removing them; as many 



as twenty-seven were taken from an Ascidian about five 



inches long. 

 M. discors, L. [var. semi/cevis, Jeffreys.] A few were taken 



in Kerrera Sound and off Fismore attached to shells, and 



in one instance to the ba.se of an Ascidian. 

 M. nigra, Gray. Several dredged alive in Kerrera Sound, 



generally attached amongst masses of Modiola modiolus. 



The largest valve measures 45 mm. in length. 

 ** Crenel la decussata, Mont. Dredged alive and dead 



sparingly. 

 Pectunculus glycinneris, L. [A.M.N. ; a few adults dead, 



some young living, R.D.D. MS.]. A dead specimen with 



the valves still united off Maiden Island. 

 Area lactea, F. [Jeffreys ; R.D.D. MS.]. One live specimen. 

 A, tetragona, Poll. [A.M.M.] Two dead and worn valves, 



and a fragment of a valve with the filamentous epidermis 



attached. 



