19 
surface of the cranium is thrown into wrinkles which form no regular pat- 
tern, and which inosculate to a moderate extent, most so on the preorbital 
region. ‘The anterior parts of the maxilliary and mandibular bones are 
marked with small pit-like impressions. 
Measurements. M. , 
Total length to quadrate angles measured on median 
MN iste etn edie tees nciedoucs sibiahaiaie rege ieee salsa 170 
Length to supraoccipital border......... troseseeessg ee oLBS 
Total width posteriorly......... eitewsnhls oi ew Means 155 
Width at orbits.............. Seipiualein aed eexanaeuess « 095 
‘* between orbits........... ce ern ee veee 021 
ab DATS ss wedncdes see 2 PAUSES Esch sineiesawwe 6 068 
¢ Debween Nares....6.5 secs cence nee ee oeavtawewne 2030 
Long diameter of orbits.........2.... 05 6 she Sticcelgletelgies 026 
Transverse diameter of occipital cotylus ere sadeveiecs.. A012 
This cranium is much shorter and wider than that of Archegosaurus 
decheni, and has the orbits more anteriorly placed. 
CROSSOPTERYGIA., 
ECTOSTEORHACHIS Cope, gen. nov. 
Tribe Crossopterygia ; family. Rhombodipteride Traquair; sub-family 
Saurodipterint Huxley. Pectoral and ventral fins rather acutely lobate, 
with few or no radii on their external borders. Dorsal and anal fins uno- 
known. Scales imbricate, rhombic, smooth. Ganoine wanting from top 
of head in specimens examined, but present on sides and inferior surfaces. 
Coronal suture distinct. End of the muzzle covered with separate scales. 
Distinct sub- and postorbital bones. Gular bones, an anterior azygus and 
two laterals on each side, the posterior the shorter. Teeth acutely-conic, 
rather small ; a few large ones at the anterior part of each jaw. Verte- 
bral centra represented by osseous rings which enclosed a notochord. 
This new genus is apparently nearly related to Megalichthys, and ina 
less degree to Osteolepis and Diplopterax. Pander, Miller and others repre- 
sent the ventral fins of the two genera last named as not lobate, but sessile, a 
state of things entirely different from what is observed in Ectosteorhachis. 
The sub-division of the dermal bones of the muzzle is also rather character- 
istic of Megalichthys. From.the latter genus it differs in the form of the 
vertebral centra. Both Agassiz and Huxley describe those of Megalichthys 
as completely ossified, and as biconcave. In Eetosteorhuchis they are repre- 
sented by annular ossifications resembling somewhat those of the stegoce- 
phalous genus Cricotus, but with a larger foramen chorde dorsalis. 
The elongate-lobate axis of the fins of this genus render it probable that 
those of Megalichthys present the same character. 
EctosTEORHACHIS NITIDUS Cope, sp. nov. 
This fish is represented by several specimens, the best preserved of which 
includes the head and body inclusive of the ventral fins. These form an 
chtbyolite nearly denuded of matrix, the inferior side being best preserved. 
