890 DR. R. W. SHUFELDT ON THE OSTEOLOGY OF THE [DeC. 1, 



A pterygoid is a delicate and nearly straight rod of bone, articu- 

 lating with the palatuie in the manner just described, and with the 

 corresponding quadrate by means of a cup-and-ball joint, the latter 

 element developing the convexity for the pur|)0se. 



The rostrum is transversely very broad behind, vrhere it is likewise 

 longitudinally excavated. As it is produced forwards, however, it 

 ascends, becoming gradually narrower, convex from side to side, to 

 finally abut against the under aspect of the cranio-facial region, 

 where we find that its anterior margin has at last attained a sharp 

 edge. It is lumecessary to add, that this latter portion of the 

 rostrum is made up of the ethmoidal bone, the two imperceptibly 

 merging into each other in the Humming-birds. 



Some of the characters thus far described, as they are found to 

 exist at the under side of the skull of TrocMlus, are curiously 

 suggestive of the strnthious type of structure, more especially the 

 exposed and broad rostrum behind, and the method of finishing off 

 of the maxillaries and maxillo-palatines in front. T. alexandri has 

 the basi-temporal region of its skull very deep, and wide from side 

 to side. It is pierced at about the usual sites by foramina for nerves 

 and vessels to find their exit from, and others to enter the cranial 

 casket. The plane of the foramen magnum is nearly coincident 

 with that of the basis cranii ; and this aperture is very large compara- 

 tivel)', and of a broad elliptical outline. On the other hand, the 

 condyle is notably minute in its dimensions, and of a hemispheroidal 

 form. 



The mandible of the Alexander Humming-bird is seen upon lateral 

 view iu Plate LVIII. fig. 2. It will be observed that it is quite 

 as delicately fashioned as the remaining half of the beak above. Its 

 hinder fourth is bent downwards, and a well-marked ramal vacuity 

 exists. Viewed upon its superior aspect, this bone has a very acute 

 V-shaped outline, with rather a long symphysis, which latter is 

 excavated in the longitudinal direction above. Either articular end 

 presents a very shallow facet on its upper side ; behind, its angle is 

 truncated, while the in-turned processes of the ramal limbs at this 

 extremity are well developed and point directly towards each other, 

 being perpendicular to the median plane. This bone is largely 

 pneumatic. 



The elements of the hyobrancJiial apparatus are absolutely fila- 

 mentous iu character, the greatly lengthened thyro-hyals curviug 

 well up behind the occiput, alter the style of some Woodpeckers. 

 The first basi-branchial is very long and straight, while the second 

 one is reduced to a mere rudiment ; both are independent bones and 

 the heads of the ceratobranchials articulated at the sides, where they 

 meet each other. 



The ceratohyals and glossohyal do not ossify in this Humming- 

 bird. 



Having examined the skeleton of Trochilus thus far, I will now 

 briefly present the characters of the same part as they are found in 

 the two remaining groups, taking up the Goatsuckers first. After 

 that, it is my intention to discuss the balance of the axial skeleton 



