56 
Two specimens of this Asaph are in the cabinet of 
the Albany Institute. The one from which our cast 
is taken, was found on the Helderberg mountains; it. 
is embedded in a light grey coloured limestone shale. 
The other specimen, which is much smaller, was dis- 
covered near the Genessee river, in the State of New 
York. The rock in which it occurs is identical in 
its constitution with the other. It contains other 
species of trilobites, and a number of shells. 
¥ { , , 
-o./¢ Asapous Micrurvus.* Cast No. 19. Fig. 3. | 
ite . jy | 
Cauda attenuata, acutas corpore valde convexo; 
costis striatiss; parte marginali vix membranacea. 
This fine, large caudal termination of an Asaph is 
in the cabinet of the Albany Institute—and it is a 
subject of great regret, that all that has yet been dis- 
covered relating to this highly interesting trilobite, 
is to be seen in this fragment. | 
There are eighteen articulations of the tail and 
abdomen, which cannot be distinguished from each 
other. The middle lobe is composed of a series of 
straight, distinct, parallel articulations, very convex 
about the middle, so as to form a kind of longitudinal 
ridge down the back. The costal arches of the 
lateral lobes are very distinct, and are longitudinally 
striated or grooved on their upper surface, particular- 
ly those near the upper part of the animal. “The 
membranaceous expansion is very narrow along, the 
: int Fs ity a 
* From the Greek, for “ minute tail.” cS ES 
