N 



Family Scymmiidt. 

 489. A dried specimen of a small Shark of the genus Srymntu. 



The teeth of the upper jw are small, conical, subcomprawed, with slightly recurred point*. 

 The teeth of the lower jaw are about eight times larger than those above : they are straight, 

 flattened, symmetrical, lancet -shaped plates, with finely dentated margins: one of them 

 croms the line of the symphysis of the lower jaw. 



Presented by F. D. Bennett, %., F.L.S. 



Family Squafinida. 



440. The cranium with the maxillary and mandibular arches and the labial cartilages 



of the Monk-fish (Squatimi Angeltui). MM. lleari*ide. 



441. The maxillary and mandibular arches of the Monk-fish (Squatina Angeln9). 



442. The skull, with several anterior abdominal vertebrae and the branchial arches, 



of the Monk-fish (Squat 'JIM Angcluj). 



This specimen has been vertically bisected, showing the form of the cranial cavity and of 

 the biconcave spaces between the bodies of the vertebra. The body of the atlas has coalesced 

 with the basioccipital, but the neural arch remains distinct ; the gelatinous mass between the 

 atlas and axis has been ossified and has coalesced with the body of the axis. The distinction 

 between the hyoidean and the branchial arches is well shown. The hyoidean arch is sus- 

 pended from the tyrnpano-mandibular joint, and supports six branchiostegal rays. The upper 

 or cpihranrhial element of the first gill-brariug arch almost meets its fellow beneath the an- 

 terior abdominal vertebra, to which it is attached by a ligament. The bases of the cerato- 

 branchials expand into triangular plates which underlie the extremities of the hypobranchial 

 processes. The last arch presents an exception to this structure. 



Pretexted by Joseph Andre, Esq. 



443. The cranium, with the upper and lower jaws, of the Hammer-headed Shark 



(Xyyerna laticep*. Cantor). 



It is chiefly remarkable for the extension of two long processes outwards from the antero- 

 laieral parts of the cranium ; which processes bifurcate at the extremity where they form the 

 orbits. On the left side some of the elongated muscles of the eye are preserved. The rostral 

 prolongation is short and obtuse, bat is supported by three processes as in the normal Sharks, 



of 



