OF THE SKULL IN THE AMPHIBIA URODELA 209 



and Menopoma. I have worked it out in Siren, Sieboldia, and Menopoma, and am con- 

 fident of its real nature ; it is twice as large, and not confluent, in Proteus. 



Plate ii. In fig. 22, Op, a stapedial stem is figured in Cryptobranchus as well as in 

 Menopoma (figs. 24, 25). This is the curiously modified pharyngo-hyal cartilage and 

 stapes, confluent. 



Plate v. In Ellipsoylossa (fig. 65), in Banodon (figs. 69, 70), and in Amblystoma punc- 

 tatum (figs. 76, 77), the hyomandibular {II. F.) is shown ; in Banodon there is evidently 

 an additional stem to the stapes {Op). 



The antorbital (" ethmo-palatine ") cartilage is shown (A.F.) to he confluent with 

 the pterygoid process of the suspensorium {Ftc) in Banodon (pi. v. figs. 69, 70), a 

 most important modification; for in the Batrachia that is a primary state of things, 

 which here is manifestly caused by confluence of the parts. 



In the Toads (Bufo vulgaris, pantherinus, &c.) the subdivision of this part is secondary, 

 both of the palatine from the pterygoid and of the former from the trabecula. 



In pi. vii. fig. 94 another most important exceptional condition is shown in Batra- 

 choseps, which is common enough in the Batrachia, viz., a large fontanelle in the roof of 

 the skull, arising from the deficient growth of the frontals and parietals. 



In pi. i. fig. 8 (Bs.H, U.p.H?) the hyoid of Amphiuma is shown to be broken up, 

 distally, into even more pieces than I have found in Menopoma, where each hypohyal 

 is composed of three cartilages. A curious thing also occurs in Osseous Pishes, where 

 the hypohyal segment, quite distinct, is ossified by two centres. 



The figures of transversely vertical sections of adult skulls and the various modifica- 

 tions of the hyobranchial arches in the adult are beautifully perfect, copious, and 

 instructive. 



The remarkable {Petromyzine) " cavum intermaxillare resp. nasale (CI) is shown in 

 most of the types. I know of nothing in the morphology of the skull more tantalizing 

 than these structures. Surely some low ichthyic types will help us to connect this 

 structure with the azygous nose of the Lamprey *. 



* Dr. Wiedersheim's description of the skeleton of Pleurodeles Waltlii (Alorphologischo Studien, plate ii. figs. S— 10, 

 pp. 27-42, Jena, 1880) may now be added to the above. 



