PRIMORDIAL CRANIUM OF THE CAT 343 



cartilages. It is not clear from the description that there are 

 two separate elements present. The term "investing mass" is 

 misleading with respect to the notochord ; Parker expressly states 

 that the former Ues beneath the notochord and so represents 

 the relations of these two parts in the figures. Froriep ('86) 

 recognized a tendency to the formation of bilateral symmetrical 

 anlagen of the caudal part of the occipital floor in the calf (p. 

 91, woodcut to fig. IV, fig. IV, 2). This author remarks on the 

 striking difference between cervical vertebrae and the occipital 

 vertebra presented by the bilaterality of the anlagen of the 

 bodies. In the former it becomes more pronounced in the 

 cranial direction, whereas in the occipital vertebra this con- 

 dition is presented in a lesser degree. In reference to the anlage 

 in the occipital floor, Froriep says: " In einem Querschnitt dagegen 

 wie Fig. IV, 2, ist eine bilaterale Sonderung des Knorpelgewebes 

 nicht zu bemerken, die Knorpellage ist hier ventralwiirts der 

 Chorda fast ebenso machtig wie zu beiden Seiten" (p. 91). 



In the fight of recent studies the condition represented in the 

 figure might justly receive a different interpretation wdth respect 

 to bilaterafity of the anlage; the figure shows two cartilages in 

 the occipital floor, one on each side of the notochord and some 

 distance removed from it, united by continuous cartilage across 

 the midline ventrad of the notochord. Levi ('00) described a 

 pair of precartilaginous and cartilaginous anlagen for the middle 

 piece (basilar portion) of the occipital region in a human embryo 

 of about 13 nmi. These were united across the midplane by 

 connective tissue in which ran the notochord, and which was 

 continuous in a caudal direction with the connective tissue of the 

 first cervical vertebral arch (p. 355). Bardeen ('08) also ob- 

 served the beginning chondrification of the base of the occipital 

 in man' in two bilateral centers. Other investigators have 

 recorded an unpaired chondrogenous beginning of the occipital 

 basal plate, or, again, its development in connection with the 

 lateral occipital arch. Weiss ('01) found, in the white rat, that 

 chondrification of the floor of the occipital region was mani- 

 fested, first, by centers in the hypochordal region, one of them 

 in Froriep's apparently unsegmented portion, the other in the 



