MOLLUSCA OF PLYMOUTH. 455 



36. PoLYCERAj Cuvier. 



51. *P0LYCEKA QUADBILINEATA, Milller. 



Ml'. Cunningham's bottom tow-net, designed for catching young 

 flat-fish, brought up several specimens when shot in Cawsand Bay 

 on May 14th and June 25th. The bottom here is sandy, and 

 Zostera marina, Ceramium., Antith amnion, and other weeds are abun- 

 dant^ over certain areas. The Nudibranchs were among these weeds 

 when caught. One individual possessed six frontal filaments, and 

 no tubercles at all. The yellow colour was confined to the frontal 

 and " branchial " (pleiiropodial) processes, the rhinophores, and tips 

 of the branchias. 



Three fine specimens were taken by Dr. Fowler on a piece of drift 

 weed at low water, east end of Drake's Island, on July 16th ; and 

 three more were found upon Fiicus and Ulva by Mr. De Hamel 

 between tide-marks near the same spot on August 18th. There 

 was much spawn near them at the time of capture, and they con- 

 tinued to deposit it for many days. In captivity, though healthy 

 and with plenty of weeds, they were reduced in size by the end of 

 the month. 



This species, as Alder and Hancock inferred, is undoubtedly her- 

 bivorons in habit ; one or two of the specimens mentioned in my 

 former report were dredged in weedless ground, but all the others 

 have come from localities where algse are abundant. 



52. ■^PoLYCERA Lessonii, B'Orh., var. ocellata," A. and H. 



At extreme low water on the north side of Drake's Island, June 

 3rd, I found what was almost certainly another specimen of this 

 variety under a small stone. Unfortunately it was lost, owing to 

 the breakage of a collecting bottle, and was not very closely exa- 

 mined beforehand. 



37. Triopa, Johnston. 



53. *Triopa clavigera, Milll. 



Another specimen was again dredged off the Mewstone, about 

 two miles south, in the middle of April. The pigment spots on the 



' See Prof. Johnson's paper on The Flora of Plymouth Sound, this Journal, New Series, 

 I, iii, pp. 297, 298. 



' I have followed Dr. Norman in placing ocellata as a variety of Lessonii, Herdman 

 and Clubb (Second Report, 1889, p. 227) have noticed the intermediate variations, but it is 

 interesting to note that the type and the variety seem to live, as a rule, under different 

 conditions of depth and food (see Alder and Hancock, Monograph). 



