No. 382.] DINICHTHYID OSTEOLOGY. 755 
Dinichthys intermedius Newberry. 
Fig. 3 shows the arrangement of cranial and dorsal shields 
in this species, as determined from specimens in the Museum 
of Comparative Zoology. The diagram of the head is based 
on a cranium that has already been described with considerable 
detail by Claypole,! and his figure was copied with slight modi- 
fications in a former paper by the writer.? The present figure 
does not differ materially from either of the preceding ones, 
except that the boundaries of a few plates are slightly altered, 
the position of the pineal foramen is indicated, and the subor- 
bital and opercular (“ postmaxillary ” Newberry), which do not 
properly form a part of the head shield, are here omitted. A 
supernumerary sensory canal, thought by Claypole to extend 
along the boundary between the pre- and postorbital plates 
near the orbits is also suppressed, as nothing but the suture 
was observed in this region. The pineal plate has been short- 
ened somewhat, but its outline is still conventionalized after 
Claypole’s figure, the element itself being missing from the 
specimen. In D. terrelli and D. pustulosus this plate is rela- 
tively shorter and narrower than here represented, but owing 
to its tenuity, is seldom well preserved. 
As already remarked, the writer has not been able personally 
to observe a division of the central element into two plates, 
termed by Newberry, Claypole, and others the “ parietal ” and - 
“frontal.” The boundary, as depicted by Claypole, has been 
allowed to stand in dotted lines on the present figure, but the 
two portions occupying the space of the central are designated 
C! and C2, instead of by the misleading terms commonly applied 
to them. If two plates could actually be shown to exist here, 
the terms central and precentral would be decidedly more fitting. 
It is true that in Phlyctanaspis a division of the marginal into 
two separate elements, angular and marginal proper, has been 
noticed by Traquair; and unless von Koenen* has mistaken 
the initial portion of the preorbital canal for a suture, a similar 
* Loc. cit. ered 2 199-207. 
2 Bull. Mus Zool., vol. xxxi (1897), PI. 2 Fig. 1. 
8 Ann. Nar a eas [6], vol. xiv (1894), p 
4 Abhandl. Akad. Wissensch. Gottingen, Bd. # 11895), Taf. II, Fig. 6. 
