Massy — The Holothiirioidea of the Coasts of Ireland. 49 



one September haul the tubes were observed to be full, but usually, as far as 

 examined, they were empty in August and September. 



Distribution. — Plymouth. Probably distributed on the Continent, but 

 passing under another name (Orton, 1914). 



Thyone fusus (0. F. Miill.), 1788. 

 „ fusus, Diib. & Kor, 1844. 

 ,, papulosa, Forbes, 1841. 



Nichols (1903, p. 243) enumerates 5 records of the occurrence of this 

 species on the west coast of Ireland, and 7 records in the Irish Sea, 

 from Larne to Dublin Bay. We have trawled a specimen off Chicken Eock, 

 I.O.M., and another example, apparently referable here, but of which the 

 spicula had dissolved, was taken in St. George's Channel. From 51° 28' IST. 

 to Clew Bay we trawled it in 18 hauls at soundings of 2-342 fms. Usually 

 only 1 or 2 specimens occurred, but 5 were observed on one occasion (in 

 22 fms,, on gravel and stones, off Dingle Lt. Ho.). 



In size our specimens varied from 6-105 mm. A number of specimens 

 from 17 to 78 mm. in length were found to possess 1 simple polian vessel, 

 sometimes dilated in the middle. The smallest specimen with gonad 

 developed measured 8 mm., and contained 8 gonadial tubes. A specimen of 

 17 mm. possessed 50 tubes, somewhat welded together. The tubes are very 

 fine and narrow. 



A specimen of 52 mm. contained about 650 tubes of about 15 mm. in 

 length. An example of 78 mm., with collar of 23 mm., taken by Mr. Nichols 

 in Baiitry Hay, aud now in the Irish National Museum, contained about 

 200 tubes, measuring about 2o mm., and a polian vessel of about 14 mm. 



Distribution. — Lofoten to British Isles, France, Mediterranean. 



Thyone raphanus, Diib. & Kor., 1844. 



This species has previously been recorded only from our south-west coast 

 (Nichols, 19(i3). We have taken it twice in the Irish Sea. namely, off Black 

 Head, Co. Antrim and off Chicken Eock. I.O.M., and 8 specimens occurred 

 in two hauls off Co. Waterford. We also obtained it in Dingle Bav and 

 Bantry Bay. Our specimens were trawled at soundings of 16J-45 fms. Once 

 the bottom was muddy sand, and the other hauls occurred on fine or coarse 

 sand, or on a bottom of gravel and shells. Some specimens examined 

 measured 10-23 mm. All had an unforked polian vessel, dilated in one or 

 more places. Specimens of 15-16 mm. possessed 60-90 gonadial tubes, and 

 one of 23nim. had at least 120 tubes. The sexual products were more 



