Mr. W. Thompson's Additions to the Fauna of Ireland. 237 



XXII. — Additions to the Fauna of Ireland. By William 

 Thompson, Esq., Pres. Nat. Hist, and Phil. Society of Belfast*. 



[Continued from p. 176.] 



Crustacea. 



Order Decapoda. 



1. Stenorhynchus tenuirostris } Leach. 



On examining some fine Stenorhynchi dredged in Belfast bay from a 

 depth of twenty to twenty-three fathoms (shelly sand) in Oct. 1846 

 by Mr. Hyndman, I found that like specimens obtained there, but 

 from a much less depth, some years before, had more characters in 

 common with this species than with S. phalangium. The rostrum, 

 though longer than in the latter — three lines in length in a specimen 

 whose carapace from its base to the hinder extremity is ten lines — 

 is not of the extreme length of that of S. tenuirostris : — instead of 

 being " longer than the peduncle of the external antennae," it is not 

 so long. But " the series of minute spines on the inner part of the 

 arm, the body altogether more elongated, and the spines more acute" 

 than in S. phalangium, mark my specimens as S. tenuirostris. 



The preceding notes were made on a comparison of these examples 

 with the descriptions of Leach and Bell. Having subsequently taken 

 specimens to London and compared them with those in the British 

 Museum described by Leach, the result was the same. I therefore 

 look upon S. tenuirostris and S. phalangium — although extreme forms 

 are very distinctly marked— to be in reality but one species. It may 

 be added, that in one of the two Irish examples of what I iiave called 

 S. tenuirostris taken to the British Museum, the wrist has the form 

 attributed to that species, and in the other, that attributed to S. pha- 

 langium. Both of these individuals were added to that collection. 

 The Sten. Egyptius, Edw., it need hardly be remarked, is quite dif- 

 ferent from those under consideration ; it is alluded to in consequence 

 of being the only other species of the genus. 



* Teredo malleolus. I hasten to correct an error respecting the species 

 so called at p. 163 and p. 174. The opercula or pallets having since been 

 found, prove that it is not T. malleolus. They are quite similar to those of 

 the T. bipalmulata of Delle Chiaje, Mem. iv. t. 54. f. 22 and 23, and ap- 

 proximate those of the species ( T. palmulatus, Lam.) considered the same 

 by Philippi, in the first vol. of his ' Enum. Moll. Siciliae,' t. 1. f. 8 ; but if 

 the shells there figured represent perfect specimens, my species differs from 

 his. The genus Teredo seems to require a rigid revision. Having sent spe- 

 cimens to Professor E. Forbes and Mr. Hanley, who possess in London 

 much better means of working out the subject than I have, the positive iden- 

 tification of the species is left to them. The genus Teredo will I believe be 

 included in the 1st part of their • History of British Mollusca,* to appear 

 in November. Mine is at all events a form now noticed for the first time as 

 introduced by shipping to any port of the United Kingdom. 



Erratum in note to p. 161. — Instead of " The name is 1 believe unpub- 

 lished," it should be — The name was I believe left unpublished by Dr. Leach. 



