THE SKELETON OF THE BLACK BASS. 315 



pare them in the following manner: One head is to be macerated in warm water until 

 all the soft parts can be removed and the bones separate from each other, except those 

 in the cranium. Each boue should be removed by itself, laid out to dry in a relative 

 position it occupied in the skull, and identified if possible. For this latter operation 

 the second skull is intended, and this one should also be partially macerated, but only 

 so far as to moderately soften the tissues; then by the most careful dissection, all of 

 these should be removed, and the entire osseous structure of the head left precisely as 

 it is in life, in so far as the bones are concerned, the latter beiug held together only by 

 their ligaments. This prepared skull is then properly dried. The third head, prepared 

 exactly like the second, is longitudinally sawed in two by means of a very line saw, 

 passing to one side of the crest of the supraoccipital. By means of these two halves 

 we are enabled to study the osseous parts of the interior of the brain case and the 

 bones at the anterior extremity of the skull. 



Fig. 3 of the present paper, as well as the illustration of the skull of the large- 

 mouthed black bass in fig. 2, will give an idea as to how the bones are normally related 

 to each other, and as shown in the heads of the two species of Micropterus jirepared 

 by the second method. Fig, 21 of my memoir on Amia calva shows the head, or rather 

 the cranium, of a yellow perch {Perca fiavescens) longitudinally bisected in order to 

 bring into view the bones in the brain case. 



As has beeu stated, if the head of this bass is allowed to macerate in water for a 

 sufficient length ot time all the more loosely attached bones, including .the occipital 

 nbs (fig. 1, oc. r.), will come away and separate from each other. This leaves the cranium 

 all in one solid piece as shown in fig. 1. This, as has likewise been said, is composed 

 of its own bony cranial segments, which require more protracted maceration to sepa- 

 rate them.. This cranium, and many fish possess one a good deal like it, is of a 

 pyramidal form, the base being formed by the occiput and the apex by the vomer («o), 

 which is here produced downwards as a j)rominent beak, being rounded in front, and 

 thickly studded with fine teeth upon its inferior surface. 



A very noticeable feature of the cranium are the orbits. These are large and in 

 no way separated from each other by an osseous medio-longitudinal plane standing 

 between them. Above, they have a wide, arched roof, concave from before, back- 

 wards; while below there is but the median rod, composed principally of the vomer 

 (ro.) and the parasphenoid (Pr. 8.). Other bones entering into the bounding walls of 

 the orbits are the frontals above [Fr.), the prefrontals anteriorly (Pr/.),the alisphenoids 

 {As.), and the postfrontal {Ptf.). On top of the cranium, behind, and occupying its 

 hinder half, there are five conspicuous crests, a median one and two lateral ones on 

 each side. These are well shown in fig. 1, and have been fully described in my Amia 

 memoir. They vary greatly in the crania of different species of fishes, being entirely 

 absent in some species and very prominent in others. 



In the common cod (Gadus), for example, the median crest is thick, strong, and 

 high, and produced far backwards and to the front to a point over the center of the 

 orbits. Again, in the black sea-bass {Gentropristes striatus), of which I have prepared 

 one or two perfect skeletons, these crests are more as in Micropterus, but by no means 

 exactly the same, as these two species belong to very distinct families. At the back 

 of the cranium there are to be noticed chiefly the circular, conically concave facet 

 for the atlas vertebra, with above it, one upon either side, the pair of zygapophysial 

 facets for the corresponding ones on the same vertebra. These have above them 



