SPECIMENS OF CRYPTOLITHUS. 
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that of Trinucleoides reussi (Barrande), the only other trinucleid 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 Triarthriis, 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 Triarthriis. 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- 
thriis, but nothing conclusive is shown. 
