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XXII. 



THE GYMNOSOMATOUS PTEKOPODA OF THE COASTS OF 



IEELAND. 



By ANNE L. MASSY. 



[COMMUNICATED BY ERNEST W. L. HOLT.] 



(Plate VIII.) 



[Eead June 26. Published July 12, 1917.] 



The species listed here were taken during the course of investigations carried 

 out on board the Department's fishery cruiser " Helga." The area explored 

 included the waters off the west, south, and east coasts, from the latitude of 

 Aran Island, Co. Donegal, to that of Cahore Point, Co. Wexford. The hauls 

 were made at all seasons of the year, from August, 1901, to May, 1914. 



The minute size and extraordinary powers of contraction possessed by 

 these little animals render it impossible in some instances to distinguish 

 nearly allied species without following Bonnevie's plan (1913, p. 59), of 

 dissecting out the buccal parts and boiling the radula and hook-sacs in caustic 

 potash, even if the species seems to be represented by only a single specimen. 

 Over 120 of the specimens recorded here have been thus investigated. Of 

 the 12 species, 6 appear to be new to science, and 4 have not previously 

 been recorded from the British and Irish area. 11 species occurred over 

 soundings of deep water, chiefly between latitudes 50° and 52° N., and 

 between longitudes 11° and 13° W. One of these, however, Pneumoder- 

 mopsis paucidens (Boas), appears to resort chiefly to shallow water, occurring 

 more or less inshore at all seasons from Inishbofin, Co. Galway, to St. George's 

 Channel. This would appear to be the only species in the present list 

 occurring in sufficient numbers to be of value as a fish food. The records 

 show that it was very numerous, larval specimens predominating, off the 

 Fastnet, in autumn, 1903, 1908, and 1911, and larvae were abundant in 

 autumn, 1905 and 1912, off the Blaskets, Co. Kerry. It should, however, be 

 remarked that two-thirds of the hauls in which this species occurred were 

 made in autumn. The only specimen of Cephalobrachia Bonnevii, sp. n., 

 occurred off the Blaskets. Pneumodermopsis oligocotyla, sp. n., and Thliptodon 

 atlanticus, sp. n., were found furthest north, occurring close together at about 



SCIENT. PROC. R.D.S., VOL. XV., NO. XXII. 2 O 



