/ 
_I know, he observes, only the tail of this Asaph, 
but it is so different from that of other trilobites, that 
I do not hesitate to establish a particular species, 
upon the consideration of this part alone. Its gene- 
ral form is that of a semi-ellipsis; the middle lobe re- 
presents a very slender cone. The arched ribs of the 
lateral lobes are perfectly distinct and simple. I can- 
not perceive in them the slightest appearance of bi: 
-furcation. This sufficiently characterizes the species. 
But that which further distinguishes it from the 
ethers, are the small, elevated points, scattered, and 
ef course rough (serrés), with which the skin or epi- 
dermis is covered, resembling, in this respect, the 
tail of the Zpus aniriinats hens 
This fragment of an Asaph is in a sla iieace 
compact, blackish limestone, which. centains no 
other kind of petrifaction. I know not where it was 
found. It is in the cabinet of M. de Drée. 
: On plate 2 of Professor Brongniart’s work, he ‘has - 
given figures to illustrate this species; fig. 3 A. re- 
presents the whole fragment, and 3 B. two of the ribs 
of the lateral lobes, magnified to show the arrange- 
ment of the tubercles, which are very peculiar. 
From the above description it will be readily per- 
ceived, that the A. Hausmanni comes: very near to 
the A. Laticostatus. There are, however, many 
striking differences, which will be obvious to those 
who compare our cast with the figures of Brong- 
niart. The shape of the ribs, and the tubercles upon 
them; the form of the middle lobe and of the inter- 
‘stices between the articulations, are all peculiar to 
E2 
