110 On the Astacillce of Cor diner. 



and Stenosoma by the greater length of the fourth segment of 

 the body, and the natatory character of the four anterior pair 

 of legs. 



The recent publication of the third edition of the invaluable 

 '^ Regne Animal" of the modern Aristotle, has unfortunately 

 added another synonime to the group, the history of which we 

 have been attempting to trace. The deservedly celebrated 

 entomologist, M. Latreille, in the fourth volume of the work 

 referred to, has instituted the genus Arcturus, which is iden- 

 tical with Astacilla, and adds, " Je n'ai vuqu'une seule esp^ce 

 (^Arcfurus tuberculatus) et qui a 6te rapportee des mers du 

 Nonl, dans I'une des dernieres expeditions anglaises au pole 

 arctique," p. 139. 



It would appear, from this notice, that M. Latreille was un- 

 acquainted with the zoological value of our Arctic voyages, and 

 suffered himself to describe as a new species, in the year 18<^, 

 an animal, the description and figure of which had been pub- 

 lished in this country five years before ; and in a work, too, 

 which might have been supposed calculated to attract the 

 notice of the continental observer. 



The genus Astacilla consists at present of two species : 



1 . A. Longicornis. The fourth segment occupying one third of the length 

 of the body ; terminal joint of the antennae composed of three 



rings. 



Astacilla, Cordiner's Ruins, No. xxi. Tab. iv. 



Oniscus Longicornis, Sowerby's British Miscellany, I. p. 31., T. 15. 



Leacia Lacertosa. Johnston, Edinburgh Philosophical Journal, 



vol. xiii. p. 220.~East Coast of Scotland. 



2.-4. Baffini. The fourth segment of the body double the length of the 

 third; terminal joint of the antennae composed of about twelve 

 rings. 



Idotea Baffini, Sabine, Appendix to Parry's First Voyage, p. 228., 

 T. 1., f. 4. 6. 



Id. Ross, Parry's Third Voyage, Appendix, p. 117. 

 Arcturus Tuberculatus Latreille, R^gne Animal, iv. p. \22,— Arctic 

 Seas. 



Manse ofFlisk, \2th January, 1830. 



