ANOMOURA PORCELLANIDEA. 



the median region are distinct, the former being seen in a small trans- 

 verse elevation adjoining the medial line, and in a line with the post- 

 orbital angles. There is generally an angle in the lateral margin a 

 short distance behind the orbit, where there is sometimes a small 

 spine, and this angle is in many species the termination of a depressed 

 line, which passes inward and backward to the posterior limit of the 

 median region, the whole evidently corresponding to the depression so 

 common in Grapsus, and observed, also, in Eriphia; it appears to ter- 

 minate just posterior to the first or second normal tooth (tooth D or 

 E). In a few species there is a transverse depression in a line with 

 the posterior side of the median region, as in our figures of the P. 

 tomentosa and monilifera, especially in the former, and this depression 

 terminates normally just anterior to tooth S. Rarely, as in the spinir 

 frons, the surface is still more divided ; the median region shows the 

 intramedial areolet distinct from the extramedial, and is even sub- 

 divided partly into three parts in the usual way ; moreover, some of 

 the antero-lateral areolets are distinct. The system of areolets in the 

 Porcellanae, is evidently the same as in the Cancroidea. The sides of 

 the carapax may be either rounded without a margin, or thin margi- 

 nate ; and the margin may be entire, denticulate, or even spinulous in 

 part, the last being the case in the P. armata. 



The characters of the mouth and other organs are given in Ed- 

 wards's work on Crustacea, and need not be repeated. One of the 

 most remarkable peculiarities is the position of the outer antennas, 

 posterior and exterior to the eyes. The species live under stones 

 along sea-coasts, near low-tide level, also in cavities among corals, &c. 



1. FRONS SUPEKNE VISUS RECTE TRANSVERSUS, NON TRIANGULATUS. 

 PORCELLANA BIUNGUICULATA. 



Parce transversvs, valde convexus et siibglobosus, Icevis, fronte supernb 

 visa recto. Pedes antici medicares, carpo elongate, plus duplo lon- 

 giore quam lato, integro, hn-i, maim Icevi, obsolete punctatd, digit is 

 manus majori? valde liiuntlbus, superiore bene arcuate. Pedes se- 

 quentes nudi, tarso brevi, verticalher valde biimguiculato (spind ungui- 

 culatd vix breviore quam unguiculurn verum infra instructo). 



A little transverse, very convex and subglobose, smooth; front as seen 

 from above straight. Anterior feet of moderate size; carpus more 



