Coues.] 98 [June 16, 



last named bones. The alisphenoid is large, and reaches the well- 

 formed parletals, thus supporting its neural spine; it forms a stout 

 pillar on either side, is but little, expanded, and has no connections 

 whatever either before or behind, in its continuity. The diapophy- 

 sis of this segment is confluent with the squamosal, — not with the 

 petrosal, as in many mammals. The last named (otic capsule) is of 

 large size, and distinct from all surroundings. This, and the not very 

 dissimilarly shaped tympanic bulla form two large osseous masses, on 

 either side, distinct from each other and from adjacent bones, nearly 

 filling up what would otherwise be an open space between the neura- 

 pophyses of the penultimate and last vertebra}. The intercalated 

 squamosal, with its confluent mastoid, fills up what would otherwise 

 be a further vacuity in the walls of the cranium; articulating with 

 (besides the petrosal and tympanic) three of the elements of the 

 occipital behind, the parietal above, and the alisphenoid and malar 

 in front. It is of great size ; its zygomatic process is small, and 

 curved inward. The parietals are well developed, and of normal 

 characters. 



The next neural arch is mainly represented, as far as ocular 

 demonstration can go, by the singularly shaped frontal, its spine. 

 This bone has a pyriform shape; that is, it is made a cone by the 

 curling under of its sides (or perhaps of its orbital plates) until they 

 come together and coalesce below, and then suffers a constriction 

 near its anterior extremity, the small end being then drawn out, 

 and representing two-thirds of a ring which is deficient below; the 

 scroll-like nasal fitting upon the ring. The upper surface of the bone 

 is smooth, and shows the median furrow indicative of its development 

 from two centres ; the under surface is irregular, with several pits and 

 foramina. It mostly articulates with the parietals, but the lower lat- 

 eral corners touch the squamosals; it is, of course, widely separated 

 from the superior maxillary and malar, which lie some distance in 

 front and below. To the under surface of the frontal are attached 

 two anomalous bones. The inferior and much the larger of these is 

 a transversely elongated thin plate, adherent along its upper or ante- 

 rior border with the posterior border of the frontal; touching the 

 alisphenoids on either extremity ; its free posterior border, concave, or 

 nicked out, forms the anterior border of the large vacuity already de- 

 scribed as leading from the cranial cavity into the orbital fossa. This 

 bone I take to be orbito-sphenoidal, and therefore to represent the 

 frontal neurapophyses; so judging from its position and relations, par- 



