Victorian Decapod Crustacea. 57 



Caninus maenas is exceedingly abundant on the coasts of 

 Europe. 



Tribe — Brachyura anorimla. 



Family — Droniiidae. 

 Platydpomia, gen. nov. 



Carapace much flattened, subpentagonal, pubescent. 



Front bilobed, the lobes divided by a deep sulcation — above 

 this the carapace rises into a prominent arcuate ridge divided into 

 lobes and forming a false front. 



Second antennae long and fine. 



The fourth pair of ambulatory legs equal the chelae in lenghth. 

 The third pair are very short. The last two pairs of legs are 

 turned ujd above the tirst two pairs, but not over the carapace. 

 The penultimate joints of the last four legs are truncate. The 

 dactyli are short and curved. 



Abdomen, in both sexes, with seven segments. The sternal 

 sulci of the female terminate between the bases of the first 

 pair of pereipoda in prominent raised ridges which meet in 

 the centre. 



Platydpomia thomsoni, sp. nov. (Plate V., Figs. 1, 2, 3, 4). 



All parts of the carapace are covered with a shore harsh 

 tomentum. 



Carapace much flattened, and pentagonal in outline — the length 

 from the tip of the frontal processes to the posterior margin 

 equalling the width between the lateral angles. The regions are 

 faintly defined. The "linea amourica" are not present. 



The front is formed by two prominent and nearly horizontal 

 teeth, the external edges of which are smooth and turned upwards 

 leaving a large bay between them. 



The anterior fifth of the carapace is deeply concave, and 

 terminates posteriorly in a prominent, acute, arcuate ridge, which 

 extencis across its greatest In-eadth and is terminated at each end 

 by the lateral angles which are not spinose. This ridge is 

 slightly thickened and granulate, and is divided into four equal 

 and prominent lobes by three short V shaped sulci, filled with 

 hairs. Immediately Vjehind the lateral angles there is a slight 

 concavity. ^^ 



