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Bashford De^n Memorial .Volume 



little rough and often shows the ossification centres and the ossification rays. Very 

 seldom can there be found a fine tuberculation in the region ot the ossification center, 

 The present writer has seen this phenomenon only twice. Moreover, the outside of the 

 head also shows quite deep grooves for the sensory canals and the limits between the single 

 plates. The latter are, however, often very obscure. ' 



The whole head roof was in reality strongly curved from side to side and from back 

 to front. But during the fossilization process it was more or less flattened, crushed and 

 broken. Later we shall come back to this matter and see how we can reconstruct the 

 real curving of the head roof. 



The inside of the head roof shows a much more intricate picture (Text-figures 13 and 

 14, and Plate II). The hinder margin is strongly thickened. From both the joint processes 

 (Jp), massive thickenings run along the margins, meeting one another in 

 the median line at an angle of about 110° and connected, just before 

 they run together, by a thick transverse commissure (tc). The 

 triangular place between this commissure and the above 

 mentioned thickenings is occupied by a very deep 

 double socket (ds). The curved part of the hind mar- 

 gin in front of the commissure is thin {mp). The 

 structure of the joint sockets will be described in 

 detail in a later section. From the point of union 

 the single thickening continues upward along the 

 median line to about one-third of the whole length 

 of the head roof. Here it suddenly stops and 

 forms a transverse sharp limit (tri). The whole 

 of this massive part of the shield composes 

 the posterior consolidated arch (PCA) of 

 the head roof. 



The two other consolidated parts are 

 placed symmetrically along the side margin 

 of the head roof (LCP). They begin at 

 the front of the head roof and at first are 

 about one' third of its breadth, but in the 

 hinder part they narrow quickly and run 

 as a crest into the external angles of the 

 roof. For the whole of this length there 

 is a very sharp limit between them and 

 the central thin part of the roof. This 

 limit forms a step which increases more 

 and more backwardly and finally becomes 

 a high, narrow, sharp ridge (Rd). The side 

 thickenings are most solid along this inner 



Text-figure 14. 



Sections across and along the median line of the head 



roof of Dinichthys intermedius Nwb. 



Br, branch of central part; CP, central part; CR, "bridge" 

 between lateral consolidated part and posterior consolidated arch; 

 CD, cavity; ds, double socket; FP, fore, thicker portion of latera] 

 consolidated part; ht, hind thickening; LCP, lateral consolidated 

 part; mp, median point; ?ip, neurocranial process; Or, orbit; PL, 

 postcro-lateral; PCA, posterior consolidated arch; R, rostral; Rd, 

 ridge on posterior part of LCP; tc, transverse commissure; ti, top 

 impression on "bridge" CR; trI. transverse limit on front of MB. 



