SUBCLASS II 



EUCRUSTACEA— EUCAEIDA 



767 



cinus Leach, is stated to occur in the fresh-water Miocene deposits of Oeningen. 

 Archaeoplax Stimpson is found in the Miocene of Gay Head, Massachusetts. 



The Cyclometopous families have many representatives in the Tertiary and a few 

 in the Cretaceous. The earliest are of Cenomanian age, inchiding Efyus Mantell and. 



Fr(!. 1492. 

 XaiUhopsis krexsaibergmxis v. .Mpvcv. Eocene ; Kressenberg, Ba\-aiin. Male, ventral and dorsal aspects, 1/2. 



doubtfully, the Recent Xantho Leach. Tifanocarcinus and Palaeucarpilius Milne 

 Edwards, appear in the Upper Cretaceous. The Recent Panopens Milne Edwards, is 

 said to date back to the Cretaceous. In the Eocene are found Harpartocardnus Milne 

 Edwards; LoSocamwMS Reuss (Fig. 1491) ; .ra?i</io|;s?:s M'Coy (Figs. 1492, 1493) ; and 

 Neptocarcinus and Carcinocarcinns Lorenthey. The Recent genera Cancer Linn. ; 

 Atercjidis de Haan ; and Etisus Mihie Edwards, are recorded from the Upper Eocene, 



Pig. 1493. 



Xanthopsis hruckmamii v. Meyer. Eocene ; Sonthofen, 

 Bavaria. Ventral view of female, Vi- 



Fig. 1494. 



J 'aammocarcinus iLericarti (Desm.). Middle Meeressand 

 (Miocene) ; Le Gue-a-Tresmes, France (afteri A. Milne 

 Edwards). 



although the demonstration of their precise identity with Recent forms is not in all 

 cases satisfactory. 



The easily recognised Swimming-crabs of the family Portunidac are certainly 

 represented as early as the Eocene by such forms as Psammocar cinus Milne Edwards 

 (Fig. 1494); Portunites B&\\; and the Recent iVepiwMfs de Haan. The River-crabs 

 \potamonidae) are said to be represented in the fresh-water Miocene of Oeningen by 

 the Recent genus Potamon Savigny {Thelphusa Latreille). 



