SPECIMENS OF CRYPTOL1THUS. 



159 



that of Trinucleoides rcussi (Barrande), the only other trinucleicl of which the hypostoma 

 is known, except that the border does not extend so far forward along the sides, and it is 

 much smaller. 



The antennules are not inserted close to the hypostoma, as in Triarthrus, but at some 

 distance from it, and, as nearly as can be determined, directly beneath the antennal pits 

 which are seen near the front of the glabella in many species of trinucleids. 



Fig. 45. Cryptolithus tessellatus Green. Drawing of specimen 233, made by Professor 

 Beecher. X 9. Below are parts of two of the endopodites of specimen 236, showing the 

 interarticular membranes. X 41. 



The antennules are long, and are composed of far fewer and longer segments than 

 those of Triarthrus. In this specimen they converge backward, cross each other and at the 

 distal end are more or less intertwined. 



As is shown in the drawing and photograph, very little can be learned from this indi- 

 vidual about the other appendages of the cephalon. A few fragments of exopodites on 

 either side suggest that these members pointed forward and were much like those in Triar- 

 thrus, but nothing conclusive is shown. 



