4'4 Du. ^y. g. ridewood ox the cramal [May 3, 



neai-ly liorizontally aw it does in Elo'ps. The parasplienoid does 

 not extend as far l^ack as the occipital articulation, but underlies 

 the anterior two-thirds of the length of the basioccipital. The 

 eye- muscle canal in two of the specimens examined opens 

 posteriorly by an aperture which admits of the passage of a fairly 

 large sewing-needle, but the canal is blind in the third specimen. 

 The parasphenoid has a, long narrow band of numerous small teeth, 

 and the vomer bears a heart-shaped patch of similar teeth, com- 

 pletely 'or incompleteh' divided into a right and left half. 



The endosteal mesethmoid is in rigid union with the vomer, and 

 separates fairly readily from the ectosteal mesethmoid ; this gives 

 the appearance of the vomer being in part a cartilage-bone. A 

 lateral process of the ectosteal mesethmoid passes dowaiward and 

 outward to meet a forw^ard process of the ventro-lateral border of 

 the prefrontal below the nasal sac. This is not present in Eloj^s. 

 The parietal bones touch one another in the median line of the 

 head ; each is nearly square in shape. The supraoccipital does 

 not spread far beneath the parietal bones, and does not come near 

 the frontals. In the extinct species it appears to have extended 

 farther forward (see Smith Woodward, Brit. Mus. Cat. Foss. Fish. 

 iv. pi. iii. fig. 5 ; also page vi of the Introduction, in which the 

 reference to Megalops was probably intended by the avithor to 

 refer to the extinct species only). 



The posterior temporal fossa? are large and extend as far forward 

 as the orbitosphenoid bone. They communicate with one another 

 above the i-oof of the brain-case, although in Elojis they are a 

 considerable distance apart. The roof of the brain-case is formed 

 by the alisphenoids (which meet in the middle line above the 

 brain *) and by a forward gi'owth of the lower part of the supra- 

 occipital . The supraoccipital either actually touches the alisphenoids, 

 or a narrow tract of cartilage intervenes. The roof of the poste- 

 rioi" temporal fossa is formed by the parietal, squainosal, epiotic, 

 and frontal bones. The postfi-ontal is rather hollow, and forms 

 part of the external wall and flooi- of the fossa, and the pro-otic 

 also forms part of the floor. The lateral temporal groove, above 

 the articular facet for the head of the hyomandibular, is broad 

 and shallow, and is not roofed over. 



The subtemporal fossa is deep, and extends inwards and upwards. 

 It is bounded above by the squamosal, below by the exoccipital 

 and pro-otic, behind by both squamosal and exoccipital bones, and 

 in front by the pi'o-otic. The opisthotic is comparatively large. 

 Its postero-superior part, to which the deep limb of the post- 

 temporal is attached, is small and wedged in between the main 

 part of the exoccipital and the part of this bone that forms the 

 posterior boi'der of the subtemporal fossa. The lower part of the 

 opisthotic, however, extends forwards so as to form an important 

 constituent of the side of the cranium. It is somewhat bullate in 

 shape and touches the j)i'0-otic and basioccipital. This bullate 



* Hay (Zool. BiUl. ii. 1, 1898, p. 32) states that in Tarpon atlanticus the ali- 

 sphenoids meet iu the mid-line below the brain. This is not the case in the specimens 

 now under consideration. 



