82 



HIGH SCHOOL ZOOLOGY. 



Fig. 60.— Skull of Menobranch, from below. (After Huxley). 



pmx. preniaxilla ; vo. vomer ; mck. Meckel's cartilage ; pi. palatine ; ps. para- 

 si>henoid ; liy. hyoid ; sq. squamosal ; pro. prootlo ; St. stapes ; epo. epiotic. 



4. Tlie skull retains more cartilage than does that of the cat- 

 iish, and there are fewer bones to be recognised in it. (Figs. 59 

 and 60). Of the twenty-seven cranial bones present in the catfish 

 (I, 17-20), only thirteen are represented, viz., — paired exoc- 

 cipitals, epiotics, prootics, frontals, parietals and vomers, and an 

 unpaired parasphenoid. Some of the other bones are represented 

 by cartilage such as the mesethmoid and parethmoid ; the nasal 

 capsule also is a fenestrated cartilaginous capsule, but the 

 other regions are only membranous. Two new bones are pre- 

 sent, the squamosal and the suspensorium on each side, which 

 lie on the outside of the otic capsule, and thus occupy somewhat 

 the same position as the pterotic and preoperculum. 



As to the jaws, Meckel's cartilage is furaished with a dentaiy 

 and an inner splenial bone, and it is hung to the skull by the 

 Suspensorium, a cartilage which corresponds to the hyomandi- 

 bular and quadrate of the catfish. Part of the hyomandibular 



