456 DR. W. G. RIDEWOOD ON THE CRANIAL [DeC. 13, 



Clupea sprattus. There is a median fontanelle between the 

 mesethmoid and the frontal bones. 



Temporal and Preoj^ercular Series (text-fig. 123). — The post- 

 temporal is rather large and slender. It has two long limbs 

 attached to the epiotic and opisthotic respectively ; the thiixl 

 limb, that which carries the sensory canal, is very short, and 

 touches the back of the supratemporal. The supratemporal is 

 elongated horizontally ; its sensory canal, entering behind from 

 the post-temporal, divides, as usual, into one branch going 

 upward to the parietal and another which passes forward into 

 the squamosal. The axis of the upright limb of the preopercular 

 is more oblique in Clupea harengus than in Clnpea finta, and the 

 interopercular bone and the lower limb of the preopercular are 

 relatively longer. 



Circumorbital Series (text-fig. 123). — There are eight bones of 

 this series — a small nasal, and seven bones disposed around the 

 eye. The orbital ring is incomplete above. 



Text-fig. 123. 

 I/' 



hm 



pnv 



jrwc 



sop 



P^'P top q 



Clupea finta, riglit side of skull. For explanation of lettering see p. 493. 



"^ ^ 2Iaxillary Series (text-fig. 123). — The gape is bounded above 

 by the maxilla and premaxilla, both of which bear a row of 

 minute teeth along the lower edge. In Clupea harengus there 

 are rarely more than three teeth in each premaxilla, but in 

 Clupea finta the number is between twenty and thirty. Two 

 surmaxillary bones are present on each side. 



JIaoulibular Series (text-figs. 123 and 1 24, p. 457). — The mandible 

 is rather high in proportion to its length, particularly so in Cliipea 

 harengus. In Clupea finta the highest point of the mandible lies 



