MUSCLES OF CERATODUS 361 



had been seen in one stage and two cartilages in a succeeding 

 one ; but the opinion he expressed is confirmed by the 

 observations described below. 



Greil (1913), who did not refer to the observations of Sewert- 

 zoff, K. Fiirbringer, or Krawetz, stated that the Quadrate has 

 a ' processus anterior (trabecularis) ' which springs from the 

 trabecula and anterior portion of the parachordal, and a 

 Processus oticus connecting it with the otic capsule. It has 

 also (in a 11-5 mm. embryo) an inconstant, rudimentary, and 

 transitory pterygoid process at the point where the Processus 

 anterior springs from the trabecula. 



In his figs. 421-3 (pp. 1154-6) he depicted a dorsal process 

 of the Quadrate, naming it ' Proc. asc. Qu.' This, however, 

 is evidently the otic process, which passes upwards and back- 

 wards to the otic capsule. On p. 1390 and in fig. 537, in his 

 description of a 17-8 mm. embryo, he described and depicted 

 a ' Knorpelspange ' which ' stellt eine secundare Verbindung 

 des Sphenolateralknorpels mit der Pars anterior des Palato- 

 quadratus her '. This process is external to the N. ophthalmicus 

 profundus (v.), and is evidently the ascending process of 

 Sewertzoff. 



In a 17-8 mm. embryo, Greil described two or three egg- 

 shaped or oblong pieces of cartilage adjoining the dorsal edge 

 of the Ceratohyal and over which the N. hyomandibularis vii. 

 (which passes out of the skull above the vena capitis lateralis 

 and close under the otic process of the Quadrate) passes 

 outwards. In the figs. 543 and 544 he depicted two small 

 cartilages, the inner of which is ventro-external to the vena 

 capitis lateralis. These cartilages he called Epihyalia s. 

 Hyomandibularia. He also stated that a small cell-column 

 passes from the dorsal corner of the ceratohyal to the lateral 

 surface of the otic capsule and probably forms the primordium 

 of small cartilaginous collections. 



I find that the primordia of the Quadrate and Meckel's 

 cartilage are first visible in a 10-5 mm. embryo as a continuous 

 U-shaped column of cells on the inner side of the continuous 

 primordium of the masticatory muscles and Intermandibularis. 



