54 



ON THE BRACHYUEOUS DECAPODS OF THE CAPE. 



complete natural groupe. Still the " Histoire Naturelle des Crustacts" is a book full of facts, 

 which ought to be in the hands of every carcinologist. The second naturalist, above alluded to, is 

 Professor Dehaan of Leyden. He has treated the subject in another manner, and deserves to be 

 considered of a more philosophic stamp. What he has pubhshed on Crustacea in the Fauna 

 Japonica is a magnificent tribute to science. Milne Edwards rarely takes notice of any of the 

 maxillae, except the external or fifth pair; and if any objection can be made to Dehaan s 

 arrangement, it is that he likewise is not sufficiently eclectic, and appears to make too much 

 use of the organs of manducation. Nevertheless, as he rigorously follows the mode in which 

 these organs vary, and not that by which they might arbitrarily be combined, it is satisfactory 

 to find that the result, generally arrived at, very nearly approaches to the plan of nature. 

 Nothing further has been published on Crustacea of late years, unless we except some interest- 

 ing descriptions of new species by MM. Say, Guerin, Bell and others. As for M. Dehaan's 

 system, it is not completely worked out ; so that I am obliged to offer the following arrange- 

 ment, provisionally, as being that by which I have been able to express the affinities which 

 exist among the Decapods of my own collection. It will at least serve to unite all those rela- 

 tions, whether of affinity or analogy, which have been recorded by Latreille, Milne Edwards, 

 and Dehaan, and will prove that, by means of a moderate exercise of patience, order may some- 

 times be made to arise out of an apparent chaos. 



1. The modern art of describing is too often insufferably long, while human life remains short 

 as ever. I shall endeavour, therefore, as in the former paper, to condense my descriptions as 

 much as possible. 



Order DECAPODA, Lat. 



Normal Groupe. 



Brachyura, Lat. 

 Abdomen having no appen-. 

 dages attached to the pen- 

 ultimate segment. Internal 

 antennae lodged in fossulse. L 



1 Tetragonostoma. 



2 Trigonostoma. 



Aberrant Groupe. 



r 



3 Anomura, M.E. 



Macrotjra, Lat. 



Abdomen having appendages | 



, J ^ i. <! 4 Sarobranchia. 



attached to the penultimate ^ 



segment. No fossulee for 

 the reception of the in- 

 ternal antennae. 



5 Caridea, Lat. 



rOral orifice broad in front. The afferent canals of the 

 <| branchial cavity opening behind the mouth. Epistome 

 distinct. 



Oral orifice triangular and narrow in front. The afferent 

 canals of the branchial cavity opening in front of the 

 mouth. Epistome in general rudimentary. 



C Abdomen not furnished with false natatory feet. Abdo- 

 J minal appendages not forming a natatorial tail. Bran- 

 I chise lamellate. Peduncle of external antennae not 

 L covered by any moveable scale. 



f Abdomen famished with false natatory feet. Abdominal 

 J appendages forming a natatorial tail. Branchiae peni- 

 I cilliform. Peduncle of external antennae with its scale 

 L null or rudimentary. 



C Abdomen furnished with false natatoiy feet. Abdominal 

 j appendages forming a natatory tail. Branchiae lamel- 

 late. Peduncle of external antennae covered by a large 

 moveable scale. 



2. It is only with the normal groupe that we for the present have to concern ourselves. I shall 

 therefore proceed provisionally to arrange the Brachyura into Stirpes, merely observing, that in 



