64 Mr. W. Thompson's Additions to the Fauna of Ireland. 



developed species, and consequently am of opinion that what Miiller 

 considered its adult state is another species. 



Amaroucium albicans, Edw. Ascid. Conip. p. 71. pi. 1, 3 b. 



Dredged from several fathoms in Belfast bay (1839) and on the 

 Galway coast (1840). W. T. 



Mr. McCalla mentioned to me last spring that he had collected 

 this species on the Irish coast. 



Didemnum gelatinosum, Edw. Ascid. Comp. p. 79. pi. 7. f. 5 ? 



Adherent to Serpula tubularia dredged in Strangford lough, Oct. 

 1839, &c., W. T. 



A species apparently of this genus may not uncommonly be found 

 investing the stems of Halidrys siliquosa. It is of a pale gray colour, 

 and may be said to give the plant the appearance of being besmeared 

 with bird-lime. 



Botryllus violaceus, Edw. Ascid. Comp. p. 89. pi. 6. f. 4. 

 On Fuci, Belfast bay, W. T. 



Botryllus smaragdus, Edw. Ascid. Comp. p. 91. pi. 6. f. 6 ? 



A species taken at Holywood, Belfast bay, by Dr. J. L. Drummond, 

 in the summer of 1846, of which he made a drawing and noted the 

 colour, seems to be the B. smaragdus. The notes are not in sufficient 

 detail to ensure certainty. 



The last four have not, that I am aware, been made knowTX as 

 British species : — the genus Didemnum indeed seems unnoticed. Dr. 

 Scouler has met with it on the Irish coast. 



Crustacea. 



Crangon fasciatus, Risso, Hist. Nat. de I'Eur. Merid. v. 64; Edw. 

 Hist. Crust, iii. 342, 



Among Crustacea lately submitted to my examination by Mr. R. 

 Ball are two individuals of this species, which were taken by him at 

 Bray in July last. They are nearly one inch in length, and exhibit 

 masses of mature ova. The species is admirably characterized in 

 Milne-Edwards' description above referred to. Its short thick /orm 

 at once arrested my attention as distinct from that of C. vulgaris : — 

 the colour designated by the trivial nSiVixe fasciatus does not so distin- 

 guish it. One specimen exhibits a blackish band on the fourth seg- 

 ment of the abdomen and the other none ; and the greater number 

 of specimens of C. vulgaris from various parts of the Irish coast 

 examined in reference to this character have more or less of a blackish 

 band on this segment. It is slightly shown too in Sowerby's figure 

 on Leach's Malacost. Podophth. Brit. This species has not been 

 noticed as British, but has I believe been lately obtained by Professor 

 Bell. 



