n8 



magnathus. From this we should infer, that all three genera are really synonymous, but on 

 comparing the type species of each genus it at once becomes obvious, that Paragrapsus 

 H. Milne-Edwards, on account of the different shape of the front and of the abdomen of the d\ 

 is certainly distinct from CJias magnathus, de Haan. As to the differences between the two 

 genera of de Haan, it may be said, that in Helicc the lateral margins of the carapace are 

 subparallel and sometimes slightly concave, but in Chasmagnathus convergent backward ; for 

 the rest, however, they nearly exactly agree in the shape of the front and in the toothing of 

 the carapace, though there are some differences in the abdomen of the cf , the relative length 

 oC the palm in proportion to its height and the shape of the external maxillipeds (see p. 123 

 under the head of Hclice subquadratd). 



Most of the species of the three genera are most obscurely known, and in some cases 

 it is still impossible, without examining the typical specimens, to which of the genera they should 

 be referred. As far as I can tracé out, the genus Helicc includes the following species v ) : 



H. tridens de Haan 



H. latreilli H. Milne-Edwards 



H. gaudichaudi H. Milne-Edwards 



H. lucasi H. Milne-Edwards ~) 



H. spinicarpa H. Milne-Edwards 



H. crassa Dana 



Chasmagnathus sitbquadratus Dana 



Paragrapsus urvillei H. Milne-Edwards 3 ) 



Paragrapsus gaimardi H. Milne-Edwards 



H. leachi Hess (= H. pilimana A. Milne-Edwards). 



As to H. latreilli and H. lucasi I am quite at a loss how to discriminate these species, 

 and de Man, who gave an excellent description of the former, bas neither been able to 

 separate the two species, though their habitats are widely apart, which would warrant specific 

 distinctness. Paragrapsus urvillei is so insufficiently known, that I cannot include it into the 

 following key : 

 1. Lateral margins of carapace nearly perfectly parallel, 



maximum breadth lying at external orbital angle, the 



side margins of which are parallel or even slightly 



converging backward and longer than those of anterior 



epibranchial teeth. Musical crest on arm of cheliped 



absent in both sexes . //. crassa Dana *) 



1) Kingsley (1. c. p. 219) still mentions a species "-H. giiia" without mentioning the author's name and I have not succeeded 

 in getting more information about it. 



2) Ann. Sc. Nat. (3) t. 20, 1853, p. 190; Filhol, Miss. ile Campbell, t. 3, prt 2, 18S5, p. 391; K.INGSLEV (1. c. p. 220) 

 identifies this species with H. crassa. Hab. New Zealand. 



3) Ann. Sc. Nat. (3) t. 20, 1853, p. 196. Hab. Vanikoro Island. 



4) Proc. Ac. Nat. Sc. Philadelphva, 1S51, p. 252; U.S. Expl. Exp., Ciust., 1852, p. 367, pi. 23, f . S ; HELLER, Reise "Novara", 

 Crust., 1865, p. 61; Miers, Cat. Crust. New Zealand, 1S76, p. 43; KlNGSLEY, Proc. Ac. Nat. Sc. I'hiladelphia, 1880, p. 220; Haswell, 

 Cat. Austral. Cvust., 1882, p. 107; Miers. Rep. "Challenger", Brachyura, 1SS6, p. 269. Hab. New Zealand and Australia (Queensland and 



1 Wales). 



118 



