606 



Bashford Dean tAemorial Volume 



Text-figure 28 



Head of a 50'mm. Chlainydoselachus anguineus in two aspects; A in left -oblique 



dorsal view, B as seen from below. 



After Nishikawa, 1898, Figs. 7 and 8, pi. IV. 



Head Only, Dorsal View. — Nishikawa's drawing (my Text-figure 28a) was made in 

 oblique-dorsal view. In it the front head is bluntly rounded. Being drawn in large 

 scale, it shows the sensory-canal system on the head with the lateral line extending 

 backward onto the body. The small spiracular cleft is devoid of filaments. The gill-covers 

 are distended (the first very widely) and abound in external gill-filaments — some of which 

 appear to be longer than any thus far noted. It is difficult to compare this head with 

 that shown in Figure 28, plate III. 



Head Only, Ventral Aspect. — The 50-mm. head (Text-figure 28b) must be com- 

 pared with that of the 48-mm. in the same view. The heads seem (as might be expected) 

 to be in practically the same stage of development. The 50-mm. head is slightly more 

 pointed. Eyes and nostrils show no perceptible divergence in the two specimens. 

 Mouths are alike save that the upper jaw of this specimen has no fossa in the symphyseal 

 region. The gill-arches are shown widely distended and, unlike those of the 48-mm. 

 head, are filled with protruding filaments — those on the left side being the more abundant 

 and certainly the longer. They are found on both sides of the five hinder arches. The 

 gular fold is barely continuous across the isthmus. 



