ASAPHUS. 159 



Hausmanni, a Bohemian Upper Silurian fossil. There can be no reason, however, for insti- 

 tuting a new name, as that of laticostatus is not occupied for the present genus. Asaphus 

 radiatus, with which Prof. M'Coy united it, has been described above, and is a 

 totally different species, as our figures will show. 



Tail obtusely half-oval, not semicircular, gently convex ; length two and a quarter 

 inches, width three and a quarter inches. The long-conical fl.at axis, with straight sides, 

 occupies ten lines in breadth at top, and rather quickly and regularly tapers backwards 

 for five sixths the length of the tail ; it is not clearly marked out at the tip or at all 

 prominent there. It is annulated by ten flat rings, which run direct across, and are 

 interrupted in the middle (as in several species of Phacops), so as to leave a line of 

 connecting points down the centre of the axis. The furrows which separate the axis from 

 the limb are deep, though narrow, the limb itself gently convex to the very margin, 

 and scored deeply by eleven furrows, which are at first direct or only slightly oblique, 

 and radiate outwards, then at the apices enlarge and turn backwards rather abruptly. 

 They reach nearly to the margin, and invade the striated border, which is in this species 

 much narrower than usual in the genus. I suppose the caudal fascia has impressed itself 

 upon the upper surface, as is frequently the case. But this character will serve well 

 whereby to contrast the present with the next species. M'Coy's figure is not satisfac- 

 tory, and we have corrected it very carefully from the original. His figure has the axis 

 too narrow at top, and the furrows across it entire, not interrupted in the middle, nor 

 does it shew well the character of the lateral furrows, especially the upper one. 



This species differs at once from A. radiatus (fig. 1) in the narrower, longer form of tail 

 and greater number of furrows. The furrows, too, are curved, not straight, and the striate 

 border narrow, not broad, as in that species. It may be a Ptychopi/(/e, but I think not. 



Locality. — Llandeilo Plag. Maen Goran, Builth, Radnorshire (Woodwardian 

 Museum). 



[I must be pardoned for introducing here a figure or two of a species before described, 

 and figured in PI. XVI. The specimens are pressed in different directions, that from 

 Builth (Woodcut, Pig. 32) being shortened by pressure, and that from the collection of 

 Mr. Pardoe (Pig. 33) being narrowed by the same process — cleavage-action.] 



The extreme similarity of caudal shields of this fine fossil {Ogygia corndensis, Murch.) 

 to the fossil last described {Asaph, laticostatus) has rendered it necessary to show how the 

 two may be distinguished, when found in company, as they are very likely to be often 

 found, since they occur in neighbouring localities of the same rock. 



