m 



same holds for tlie region of the processus (ransversus. There is 

 likewise formed in tiie semi-segment ]ii an osseous piece connected 

 witli the osseous arch in the region of tlic arcus posterior, whicli, 

 whilst leaving the required room for the passage of a. vertebralis 

 and ramus anterior n. cervicalis, (foramen alare) assimilates with 

 the processus Iransversus. 



If this representation is correct, it is self-evident to admit, that 

 besides the above-mentioned ponticuli other elements can be indicated 

 in the dorsal region of tiie atlas, which must be reduced to the semi- 

 sclerotome la. Hereby 1 have especially in view the cranial half of 

 the massae laterales and the central part of the arcus posterior, 

 situated between the place of insertion of the ponticuli posteriores 

 into the posterior arch. With regard to the massae laterales we 

 need only pay attention to the fact, that both the ponticuli originate 

 at its upper-resp. posterior and lateral rim, and that this place of 

 origin resp. the part of the massa lateralis projecting most posteriously 

 and laterally is likewise always situated cranially from the 1^^ spinal- 

 nerve; for on this s[)ot we see, with somewhat strong development, 

 the two ponticuli assimilate into each other. Consequently we are 

 compelled to admit that here also is a part lying in the most 

 cranial region of the massae laterales, which just like both the ponticuli 

 has originated from the semi-segment la. A difficulty however 

 presents itself here for tixing the boundary-line between the regions 

 of the semi-segments la and lb. Tiiere was no difficulty in this 

 respect for the ponticuli, as all that lies cranially from the first 

 spinal-nerve i.e. over the foramen arcuale or alare does certainly 

 not belong to lb. and there is not a single inducement to admit 

 that anything of the region lying caudally with regard to that nerve, 

 should belong to the semi-segment la. Here however it is different, 

 the massae laterales show neither with the full-grown atlas nor 

 with the young one a I'elief of any morphological signification, as 

 the for. arcuale or the for. alare doubtlessly is, and that would 

 allow to indicate the boundary-line between the semi-segment la and lb. 

 We can consequently say indeed, that in all probability part of (he 

 massae laterales still belongs to the semi-segment la, for the present 

 it is however impossible to say which part belongs to it. 



For the above-mentioned central part of the arcus posterior it is 

 easier. Also in this region it is, as we saw, a priori probable, that 

 the activation of the osteogenetic potency of the semi-segment la 

 does not remain restricted to the ponticuli posteriores and laterales, 

 but extends itself between the points of insertion of the ponticuli 

 into the arcus posterior, and consc(picntly forms an in the median 



