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ultimate, rounded and somewhat gibbous ; the termina 

 one subulate and acutely pointed, the whole of them 

 strongly ciliated. The abdomen in the male is five- 

 jointed, from the soldering of the middle three joints, but 

 their distinction is still obvious from the transverse groove 

 not being obliterated ; it is narrow triangular, the last joint 

 very small : in the female the abdomen is seven-jointed, 

 and a little broader than in the male ; in both it is fringed 

 with long hair. 



Length, 0*6 of an inch, breadth rather more. 



We owe our knowledge of this rare species, as indi- 

 genous to Britain, to the researches of Dr. Melville, the 

 learned Professor of Natural History in Queen's College, 

 Galway. It was found by him buried in the sand, and 

 three specimens, one male and two females, obligingly for- 

 warded to me. Both the females were loaded with spawn. 

 Hitherto this is the only instance of its occurrence as a 

 native of our coasts. 



The species was first figured by Herbst in his great 

 work, but somewhat imperfectly ; I cannot, however, join 

 with Dr. Leach and Milne Edwards in doubting that 

 Herbsfs species is identical with that of the individual on 

 which Leach founded his Genus Thia. The habitat of that 

 specimen was unknown ; but Risso has described, under 

 the name of Th. Blainvillii, what I cannot but believe to 

 be this species. It is stated by Dr. Milne Edwards to 

 inhabit " La Manche" and the Mediterranean. 



It is right to mention that there is one character in 

 which the Irish specimen differs from the descriptions 

 given by Leach and Milne Edwards ; namely, in the 

 much shorter length of the antennae ; but Guerin's figure, 

 in the " Iconographie du regne animal," exactly agrees in 

 this respect with the former. 



