PELAGIC LIFE, FALMOUTH. 319 



MoLLUSCA. 



During the morning- of the 10th of August, 1891, the 

 steam dredger "Briton" which for some time previously had 

 been moored over a large bed of Zostera, was beached at 

 high water to have her sides scraped and cleaned. As soon as 

 the tide had left her dry, I went and examined her sides for 

 interesting specimens. Without any difficulty I found eight 

 specimens of Dendronotus arborescens, the largest measuring 

 28 m.m. in length when crawling. This moUusk appears to be 

 very rare in the south-west portion of England, since Dr. Cocks 

 does not record its capture in any of his lists, and my friend 

 Mr. Grarstang (5) has only captured two specimens of this 

 nudibranch during his residence in Plymouth. 



On the 23rd of September of the same year, on hauling in 

 my dredge off St. Mawes castle from the deep water, I found 

 therein a large stone covered with various species of Hydroids 

 and Polyzoa. When I returned to my hut, I placed this stone 

 in a large glass vessel of sea water, and shortly after was 

 pleased to see several specimens ^olis landsburgii swimming in 

 an inverted position just under the surface of the water. This 

 species also appears new to the district. I had intended 

 measuring and making additional observations on these 

 mollusks, but as the day was drawing to a close, I had to 

 postpone my investigations till the following day. Before 

 closing my hut, I placed the jar containing these nudibranchs in 

 large tray, from whence an overflow pipe conveys the waste 

 water from my aquaria into the sea. These mollusks must be 

 very active, for on the following morning they were all gone, 

 having escaped I imagine by the waste pipe into the sea. Since 

 that date I have not seen any more specimens of this nudibranch. 



On further examination of the material brought to my hut 

 on that day, I found on an old oyster valve, a single specimen 

 of Polycera quadrilineata, measuring only 3 m.m. in length. 

 On the 3rd of October following, I secured under the Eastern 

 breakwater another specimen of the same species, measuring 16 

 m.m. in length, and on the 18th of January of the current year, 

 I secured another under a stone at low water in St. Just creek. 

 Dr. Cocks records the capture of two specimens of this species 

 by Dr. Yigurs in Gerrans bay. In connection with this 



