COCCOSTEIDJR. 277 
Cp°_ Q6u*cJ*^ & l " 1 Uili * ?> tf*-'- A ^ 
Family COCCOSTEID^E. 
Cranial shield consisting of few elements :—a median occipital, 
with two pairs of bones following immediately in front, this series 
being terminated by an anterior azygous element over the ethmoidal 
region ; three lateral pairs of bones forming the sides of the shield. 
Narial openings small and anteriorly situated. Maxilla and pre¬ 
maxilla well developed, but toothless ; dentition, when present, con¬ 
sisting of conical teeth fused with the oral margin of the mandible 
and with two inner pairs of bones in the upper jaw (presumably 
palatine and vomerine). Abdominal region with a dorsal and ventral 
armature, the large dorsal plate having a deep inner longitudinal 
keel, evidentlv for connection with the neural arches of the endo- 
skeletal axis. 
Synopsis of Genera . 
I. Orbits forming notches in the cranial 
shield. 
A. No pineal foramen. 
Median hone over pineal region ; no 
pectoral spine . 
Similar, but with pectoral spine .... 
No median bone over pineal region; 
no pectoral spine . 
B. Pineal foramen present. 
Scutes ornamented with fused series 
of tubercles . 
Scutes smooth or faintly rugose; 
teeth prominent . 
Scutes smooth or faintly rugose ; no 
teeth in mandible. 
II. Orbits completely enclosed in the cranial 
shield. 
Scutes finely and closely tubercu- 
lated; cranial shield much arched*. 
Scutes finely and closely tubercu- 
lated; cranial shield nearly flat; 
antero-lateral processes of abdomi¬ 
nal shield small . 
Scutes coarsely and sparsely tuber- 
culated ; cranial shield nearly flat; 
antero-lateral processes of abdomi¬ 
nal shield enormous .. 
Coccosteus (p. 278). 
Br achy dims (p. 294). 
Phlycteenaspis (p. 295). 
Chelyophorus (p. 299). 
Dinichthys (p. 300). 
Titanichthys (p. 302). 
Macropetalichthys (p. 303). 
Homosteus (p. 304). 
Heterosteus (p. 308). 
