474 



origin to the ventral roots 

 which form the abducent. 

 The first postotic en- 

 cephalomere is the 12th, 

 that is to say tlie seventh 

 rhorabomere , which is 

 connected with the glosso- 

 pharyngeal, as the next 

 segment is with the vagus. 

 As in this posterior region 

 of the brain the encephalo- 

 meres and the somites 

 regularly alternate it was 

 only necessary to deter- 

 mine the limits of the 

 head to state the number 

 of segments completely. 

 These were found to be: 

 prosomeres 3, mesomeres 

 2, rhorabomeres 13, 



In 1903 I obtained 

 two embryos of Acanthias 

 vulgaris enclosed in a 

 single, elongated, spindle- 

 shaped capsule in one 

 oviduct, I only received 

 the portion containing the 

 egg-case and it is more 

 than likely for that reason 

 that there was not an 

 embryo in the oviduct of 

 the opposite side. One 

 of the embryos was un- 

 fortunately lost. The one 

 now to be described 

 measured 17.5 mm. After 

 being prepared it was 

 cut into a series of 

 obliquely transverse sec- 

 tions by the late E. P, 

 Witten, B, Sc. 



