Figure 74.— Lateral views of 



relatively normal balistid skulls: 



above, Batistes capriscus. ca. 360 mm SL 



Gulf of Mexico; below, B. polytepis, 



ca. 390 mm SL, Mexico. 



Other balistids. It does not project to the exterior and 

 there is no foramen in the last series of scales. In Melich- 

 thys the encasing scales are flexible in young specimens 

 but tend to become less flexible in large adults (Berry 

 and Baldwin 1966). In Canthidermis, in which the en- 

 casing scales are only slightly flexible even in young 

 specimens and more or less immovable in large adults, 

 the fin-ray element is even more reduced than in Melich- 

 thys, being only a small conelike ossification at the end of 

 the pelvis which is far too short to protrude to the ex- 

 terior even if a nonexistant foramen in the last series of 

 encasing scales were present. 



In the more generalized monacanthids there are three 

 series of encasing scales, and there is always at least one 

 region of great dorsoventral flexibility between them. 

 One of the encasing scale series of balistids has been lost, 



but the flexibility retained, as is a dorsal lobe of the pel- 

 vis to strengthen the support of the modified enlarged 

 scales of the distensible skin between the end of the pel- 

 vis and the anus. In these generalized monacanthids the 

 fin-ray element is much more rudimentary than in 

 balistids, and, in contrast to the single rodlike piece of 

 balistids (except a stubby cone in Melichthys and 

 Canthidermis), the element in monacanthids is always 

 further reduced in size and divided into a dorsal and ven- 

 tral half widely separated by the plug of cartilage on 

 which they rest at the end of the pelvis. These two splints 

 represent only the anterodorsal and anteroventral ends of 

 the element as found in balistids. As discussed under the 

 anatomical diversity of the Monacanthidae, about half of 

 the species of that family examined have the above de- 

 scribed generalized condition of the pelvic apparatus, a 



