OF KACHH AND KATTYWAR. 13 



th'eless the examination of the form has not been of the least assistance in investigating 

 the anatomy of the test. Desor {op. cit. p. 255, tab. xxx, figs. 7-10) gives the 

 generic diagnosis of Amblypygus and the essential diagnoses of the species known in 

 1858. 



Agassiz founded the genus«in 1840; and the diagnosis is as follows: — "Large 

 Urchins, depressed and circular or ovoid in outline, with thick margins. The petals 

 are largely open and extend to the margin, and they have very narrow poriferous zones. 

 The peristome is central, and more or less angular (many-cornered). There is no 

 floscelle. The periproct is very large and pyriform, and is situated on the inferior 

 surface between the margin and the peristome." 



Desor adds in a note: — "At first sight this genus greatly resembles that of 

 Conoclypeus, but difi"ers essentially from it in the absence of a floscelle. It is really nearer 

 Pygaulus in its alliances, from which it is distinguished by its shape and periproct." 



The species noticed by Desor are as follows : — 



Ambltptgus apheles, Agass. 



Amblypygus apheles, Agass. Catal. rais. p. 108, tab. xv, figs. 19, 20. 



An elongate depressed form with tumid margins. The petals are very open and 

 the poriferous zones are very narrow. The periproct is elongate and pyriform, and 

 occupies more than half the space between the margin and the peristome. This species 

 is figured by Desor, plate xxx, figs. 7, 8; the figures are reduced one third. 



Amblypygus dilatatus, Agass. 



A large species with a circular outline, very depressed. The actinal surface concave 

 and undulating. The periproct is large and elongate. 



Amblypygus Aenoldi, Agass. 



Alarge subcircular form, uniformly tumid, with swollen margins. The petals are 

 very divergent and with very narrow poriferous zones. It is slightly concave actinally. 

 The peristome is small and elongate transversely. One specimen. 



Amblypygus Ameeicanus, Mich. 



A large circular form with very tumid margins and vaulted upper surface. The 

 poriferous zones are broader than in Amblypygus Arnoldi. It is concave beneath, and 

 the peristome is smaller than the periproct, which is large and pyriform. 



This diagnosis can be nearly confirmed by examining a specimen in the British 

 Museum, but the shape is depressed and the tumid margins do not pass up to any thing 

 like a conical or vaulted apex. The abactinal surface is comparatively flat, the curva- 

 ture being very small. There is a gentle slope, equal on all sides, from the highest point 

 to the margin, and there is a slight flatness posteriorly. The tumidity of the margin 

 is remarkable, and the swollen condition reaches only a little on to the actinal surface ; 

 for when the test is laid on its abactinal surface, it will be observed that around the 

 peristome, which is slightly in front of the centre, the test rises decidedly, and forms a 

 broad concavity for a considerable space, which even includes the periproct. 



