MOLLUSOA OF PLYMOUTH. 421 



jpontia crawling over the tufts of Gladophora. Curiously enough, 

 when the -largest pool was examined again in the following August 

 not a specimen of Limapontia or Runcina was to be found, while I 

 obtained several specimens of Actseonia corriigata. 



On a subsequent visit (September 26th) I found half a dozen 

 small ones, measuring from -^ to -^ of an inch in length, in this 

 large pool and in another. Plainly the large specimens of April 

 were congregating for spawning purposes, and afterwards probably 

 died. In August the young Runcinas were too small to notice 

 easily, while by the end of September they had grown to the size 

 recorded. On this latter visit I found no Limapontia and no 

 Actseonia. 



Mr. Cocks records this species as not uncommon at Gwyllyn 

 Yase, Falmouth, on algae in pools, half-tide and low-water mark. 

 May, 1852. 



Sub-order 2— NUDIBRANCHIATA 



( = OPISTHOBRA]SrCHIA NON-PALLIATA, Lankester). 



Section A.—A8C0GL0S8A, Bergh. 

 Family— ELY8IIDM. 

 8. Elysia, Risso. 

 9. *Elysia viRiDis, Montagu. 



The bright green variety of this species occurs in the estuary of 

 the Yealm and Wembury Bay. 



Inside the Sound several specimens have been taken of the variety 

 named olivacea by Gwyn Jeffreys. On August 14th Mr. Tate dis- 

 covered one of these upon a stone dredged near the Duke Rock, and 

 Prof. Johnson brought me one found by him among some algge 

 trawled on the same day in the middle of the Sound. A week later 

 I found two more crawling over Cladophoras in a large tide-pool near 

 high-water mark below the bathing pond. In this pool they were 

 highly inconspicuous among the tufts of algae. Other specimens 

 were found in this and neighbouring pools during the same month. 

 The colour of these littoral forms was always dull, either dark olive- 

 green or brownish ; in one specimen the colour was reddish brown. 



M. Giard^ has found in the spring of the year little Elysiae hardly 

 more than a centimetre in length, of a vivid red colour with blackish 



• Giard, Bull. Scl. Fiance et Belg., 1888, p. 502. 



