T HE A iN N A L S 



AND 



MAGAZINE OF NATURAL HISTORY 



[SECOND SERIES.] 

 No. 102. JUNE 1856. 



XLI. — On the British Diastylidae. 

 By C. Spence Bate, F.L.S. 



[With three Plates.] 



The first recorded specimen of the anomalous group of Crus- 

 tacea which forms the subject of the present memoir, was that 

 figured by Col. Montagu in the 'Transactions of the Linnsean 

 Society,' vol. ix., as Cancer scorpioides. He there describes it as 

 a mutilated specimen, and the only one which he had observed. 

 The head or forepart he believed to have been wanting, and thus 

 accounted for his inability to detect the eyes or antcnnse. But 

 still, from the general appearance of the creature, he thought it 

 entitled to a place amongst the Cancri, — which term appears to 

 be with him synonymous with Crustacea, exclusive of the^Isopoda 

 and the Entomostraca, — and that it bore a near relation to Cancel' 

 esca of Gmelin. 



Say, in the 1st volume of the 'Transactions of the Phila- 

 delphia Philosophical Society,' describes a Crustacean under the 

 name of Diastf/lis, which he affirms to be of the same genus as the 

 Cancer scurpiuidcs of Montagu and the Cancer esca of Gmelin. 



In the 13th volume of the ' Annales des Sciences Naturelles,' 

 Dr. Milne-Edwards has described another specimen, under the 

 name of Cuma Audouinii; but this he afterwards, in his ' Histoire 

 des Crustaces,' qualified with a doubt as to whether it might not 

 be the immature form of some known Decapod. 



This last opinion has been recently supported by the assertion 

 of Professor Agassiz to Mr. Dana, that the Cumce were the larva? of 

 certain Macroura. Consequently the most recent and one of the 

 most important works on the subject, Mr. Dana's great work on 

 Crustacea, contains the following passage : — " But according to 



Ann. b^ May. N. Hist. Ser. 2. Vol. xvii. 29 



