We annex, froma Prof. G Green, a notice, just received, pee 26, 
1832, of a new trilobite. 
_ Asaphus Myrmecoides scdieioats depresso; costis latis, convexis, 
tuberoaiis magnis ; cauda rotunda? 
The large fragment, by means of which this species has been 
identified, is in a fine state of preservation. Thirteen costal arches 
and fourteen joints of the middle lobe, with two or three faintly 
marked articulations near its extremity, can be very satisfactorily 
made out. The costal arches are, therefore, more numerous than 
the vertebral joints; an organization not very uncommon with the 
Asaphs.- The first eight ribs and vertebra, as seen in this fragment, 
appear to have been articulated together ; after which this irregular 
structure commences. ‘The costal arches are rounded on their up- 
per surface, without strie ; broadest near their lateral extremities, 
and are, most of them, images nodulous; these nodules re- 
semble very much the protuberances on the ribs of the Pecten no- 
dosus. ‘The joints of the middle lobe are also rounded and nodu- 
lous, but on these the nodules are disposed in the form of two very 
_ obtuse paralellograms. What renders this fragment peculiarly inter- 
esting, is that the lower portion of the upper shell, along one of the 
lateral edges near the tail, is so fractured as to present the structure 
beneath the ends of the ribs which have here scaled off. At first 
sight the broad smooth edging round this part of the fossil, resem- 
bles very much the membranaceous expansion beyond the lateral 
lobes which is one of Professor Brongniart’s generic characters of 
the Asaph. This border indeed is very like the hem so strikingly 
_ exhibited in the saphus micrurus; but upon comparing the ribs 
- on the opposite side, where they are perfect, with those terminated 
by the border, it will be seen that they are much longer; what there- 
_ fore, seems to be an expansion beyond the ends of the ribs in that 
place, must be occasioned by the reflection of the shell beneath the 
_ posterior portions of the lateral lobe. ‘The inferior structure and 
~ mechanism of this part of the fossil trilobite is thus, we believe, for 
_ the first time developed. In a fine group of the Dudley fossils de- 
- posited in the cabinet of the Geological Society of Pennsylvania, a 
similar inferior reflected edge may be seen beneath the buckler of the 
Asaphus De Debuchii. It is not uncommon in many of the recent 
Crustacea, and is strikingly exhibited along the lower - of the 
: foe polyphemus. ; 
