828 Proceedings of the Royal Irish Academy. 



mg was as in M'Intosli's coloured figure {op. cit. pi. iii., 

 fig. 1), except that the dark pigment collar was behind 

 the posterior eyes, as in M'Intosh's cut (p. 167). The 

 dark pigment is quite diJfferent in character from the pig- 

 ment hands of T. melanocephalum and T. vermiculatum. Under 

 the microscope it appears as a mosaic of oval (rather than 

 polygonal) areas, the centres of which are paler than the 

 borders. The space between the eyes was occupied by a patch 

 of opaque white (gland cells), from which a narrow longitu- 

 dinal white band ran along the middle of the dorsal surface 

 to the posterior end. This band consisted of about eight 

 rows of white dots, which were at a deeper level than the 

 pigment bands, and could be traced under the dark collar at the 

 anterior end. The central stylet apparatus resembled that of 

 a specimen taken by myself at Port Erin rather than M'Intosh's 

 figui'e (fig. 5, p. 65) ; the handle being slightly constricted in 

 the middle, and the posterior portion being more swollen than 

 the anterior. The stylet was about two -thirds the length of the 

 handle. The animal was not sexually mature. 



Distribution. — Previously found only in Bressay Sound, Shet- 

 land ; and Loch Maddy, Outer Hebrides (M'Intosh) ; Port 

 Erin (W. I.E.). 



Tetrastemma dorsale (Abildegaard). 



(Erstedia dorsalis, Biirger (1895, p. 592). 



The ordinary littoral variety, marbled with dark brown and 

 chestnut, is common on all the dredging grounds in Valencia 

 Harbour, and also among weeds between tide-marks. 



A pale variety, marbled with brownish yellow, somewhat like 

 Biirger's var. cinctus (op. cit. pi. iii., fig. 27), was found inmate- 

 rial di'edged in Dingle Bay, probably on the Wild Bank, in 15-20 

 fms. A similar variety occurs at Port Erin in about the same 

 depth (bottom : gravel, shells, and JSTuUipores), and olf Plymouth, 

 among the Cellaria which abounds on the inner trawling grounds 

 (20-30 fms.). 



One or two examples approaching this pale variety were 

 also dredged in shallow water in Lough Kay and on the Nulli- 

 pore ground at Port Magee. 

 Tetrastemma nigrum, Piches. 



Tetrastemma nigrum, Piches (1893, p. 14). 



This unusually distinct species is at present known only from 



