252 S. W. Ford—Additional Embryonic Forms of Trilobites. 
As the result of some recent researches in the Primordial 
beds of Troy, N. Y., I have obtained two specimens whie 
of the pleura have the characteristic groove of Olenellus. The 
sterior margin of the head is sharply geniculated at the sutures, 
throwing the genal spines notably forward upon the cephalic 
periphery, precisely as in Paradoxides spinosus Boeck and 
pusillus Barrande (see figs. 5 and 6). The interocular spines 
Fig. 4—Young specimen of Paradozxides spinosus Boeck sp., twice enlarged. 
Fig. 5.--Very perfect specimen of P. pusillus Barrande, enlarged 10 diameters. 
Fig. 6.—Complete individual of P. inflatus Corda, enlarged 4 diameters. All 
after Barrande. 
The length of the specimen, from the middle of the front 
margin to the extremity of the third pleuron, is 0°26 of an inch, 
