MR. E. J. MIERS ON THE OXYSTOMATOUS CRUSTACEA. 241 



Chyptocnemus HOLDswoRTHi, sp. n. (Plate XXXVIII. figs. 30-32.) Carapace nearly 

 transversely oblong, with the frontal region projecting; the lateral margins nearly 

 as long as the anterior margins, and forming nearly a right angle with the straight, 

 entire, posterior margin; smooth, without granules or tubercles, convex in the 

 centre, and slightly concave towards the margins. There is a longitudinal median 

 ridge between the front and cardiac region, and a less distinct, oblique ridge between 

 the cardiac region and posterolateral angles of the carapace. Anterior legs (in 

 female) smooth, with the arm trigonous, hand slightly compressed and cristate 

 above, the margins straight, not sinuated ; fingers nearly as long as palm, meeting 

 throughout when closed. Ambulatory legs small, and entirely concealed beneath 

 the carapace. Abdomen of female broad, punctulated, 4-jointed; the terminal 

 joints coalescent. Length \ in. ; breadth \ in. 

 Sab. Ceylon. 



This species is named after its discoverer, E. W. H. Holdsworth, Esq. In C. gran- 

 dklieri, A. M.-Edw., from Zanzibar, the front is broad and truncate, the elevated regions 

 of the carapace marked with granulated lines, and its posterior border ernarginate. In 

 O. pentagonus, Stim., from Japan, the carapace is differently proportioned, the entire 

 lower surface of the body smooth, and the fingers only one third the length of the hand, 

 which has greatly expanded horizontal crests and deeply sinuated margins. 



II. Eamily MATTJTIDJ3. 



Historical Summary. — Although the remarkable crustaceans of the Oxystomatous 

 genus Matuta are among the commonest of the species of Brachyura inhabiting the 

 Oriental region, the differences in the armature and coloration of the carapace and anterior 

 legs are so slight and so numerous that their determination is a matter of great difficulty ; 

 and most of the later naturalists have been content to admit one, or at most but two 

 species, distinguished mainly by the coloration of the carapace. I have, after careful 

 examination of the large series of specimens in the British Museum, arrived at the con- 

 clusion that there are at least nine well-marked species in the national collection. 



In the following condensed summary of the history of the genus, the principal authors 

 are mentioned who have contributed to our knowledge of the classification of the species. 



Eabricius, in the Supplement to his ' Entomologia Systematica ' (1798), established the 

 genus Matuta for his previously described Cancer victor, and added another species, 

 M. planipes, which he characterizes simply as " tliorace postice striato." It is impos- 

 sible, from this brief diagnosis, to identify the species with any of those described below 

 with any degree of certainty. 



In 1817, Dr. Leach, in the third volume of his ' Zoological Miscellany,' p. 12, pub- 

 lished an article on the " Characters of the Genus Matuta, with Descriptions of the 

 Species." In this essay four species are described, and two figured ; the Matuta victor 

 of Eabricius is referred to, but not described ; no attempt is made by Dr. Leach to 

 identify with his own the species of Herbst, Desmarest, Latreille, and earlier authors. 

 The characters employed in the definition of the species are unfortunately such as vary 



