6 [Januahy, 



have inhabited this continent, and as in the existing creation Dicotyles is the true 

 equivalent of Siis in Annerica, the probability of our very distinct fossil species 

 belonging to Dicotyles is much increased ; this probability is rendered almost 

 certain, when we consider that remains of true Dicotyles have been found in 

 Illinois in company with other singular forms, (Platygonus and Anomodon) which 

 by their great peculiarities would seem to indicate a period anterior to that of 

 the Mastodon. 



The measurements of the canine are : length of enamelled surface along anterior 

 curvature 2-2 ; breadth of posterior surface -37 : radius of curvature of posterior 

 edge 2*0 ; of anterior edge 2*1. 



The Committee to whicli was referred Mr, Dana's papers on the Crus- 

 tacea of the Exploring Expedition^ reported in favor of publication in the 

 Proceedings. 



Conspectus Crvstaceorum^ ^c. Conspectus of the Crustacea of the Exploring 

 Expedition under Capt. Wilkes, U. S. N. By James D. Dana. 



PAGURIDEA, continued; and Subtribe MEGALOPIDEA. 

 I. Paguridea, continued. 



Among the species of the genus Pagurus, as restricted in my former paper on 

 the Paguridea, there are still three groups of distinct character ; one, having no 

 trace of a beak, the front being truncate, and also having the fingers opening in a 

 vertical plane, the hands being usually compressed, with commonly the left the 

 larger; a second, having a short beak or triangular point in front, and the fingers 

 opening like the preceding, with the hands subequal ; a third, having a beak like 

 the last, but the fingers opening in a horizontal plane, the hands being subequal 

 and more or less depressed, and never compressed. The first group has Pagiinis 

 punctulatics for its type; the second, P. a7iic7cl?is ; the third, P. clibanarius . 

 They form three genera with the following characters : 



1. Pagurus. Frons non rostratus, truncatus. Manus anticae saepius com- 

 pressae, interdum subacquae, saspius sinistra majore, digitis apice cornels, in piano 

 vertical! claudentibus. 



2. Aniculus, D. Frons triangulate rostratus. Manus anticae subaequae, 

 digitis apice cornels, in piano verticali claudentibus. 



3. Clibanarius, D. Frons triangulate rostratus. Manus anticae subaequa?, 

 plus minusve depressae, digitis apice cornels, in piano horizontali claudentibus. 

 Species P. ceqrialis, zebra, Jmmilis, glohosi-mcouis, Clibanario pertinent. 



The species Pagurus aniculus may hereafter be named Aniculus tyjdcris ; the 

 P. clibanarius, Cllhanarius vulgaris; and the P. Bernhardus, Bernhardus streh- 

 lonyx. The name Bernhardus pubescens, (see preceding volume, p. 270,) we 

 propose to change to B. scahricidus, as Kriiyer* has described a Pagurus pic- 

 hesceyiSf which is probably a Bernhardus. 



Descriptiones Pagurideorum adhuc ineditce. 



Bernhardus obesi-carpus. Frons medio prominulus, obtusus. Regie cara- 

 pacis antica paulo transversa, nudiuscula. Oculi crassi et perbreves, aciculo 

 longiores, squama basali ovata, subacuta, Integra. Antennae externa5 nudac, 

 basi multo longiore quam oculus, aciculo crasso, brevi, apicem articuli 3tii 

 attingente. Pedes toti fere nudi et granulosi, non armati ; antici ina^qui; manu 

 majore oblonga, convexa, symmetrica, granulis nitidis partim seriatis, carpo 

 multo crassiore, parce latiore. Pares 2di et 3tii crassiusculi, articulo 3tio supra 



* Tidsk. ii, 25] , 252. 



