424 



Bashford Dean lAemorial Volume 



The following description of the spiracles of Chlamydoselachus is based on my four 

 adult specimens, numbered I to IV respectively, of which the first three were dissected 

 by me and the fourth was studied without dissection. 



The external spiracular apertures are ordinarily very small (Text-figures 70, p. 396; 

 and 124, p. 489). With one exception to be described presently, they are mere sUts, 

 from 1 to 3 mm . long. In my four specimens each aperture is situated in Hne with the 



Text-figure 82. 

 Left internal spiracular aperture and cavity (x 1.5) of Chlamydoselachus. The boundaries 

 of the cranium, hyomandibular, palatoquadrate, caecum and spiracular canal are indicated 



by broken Hnes. 



c.l, caecum; cr., cranium; hm., hyomandibular cartilage; i.s.c, internal spiracular aperture and cavity; l.p.i., 



Ugamentum postspiraculare inferior; ]5.q., palatoquadrate cartilage (upper jaw); s.c, spiracular canal. 



Drawn from specimen No. I in the collection of the American Museum of Natural History. 



spiracular division of the sensory canal system (Text -figure 124, p. 489), about 8 mm. 

 from its anterodorsal end. In each case, the direction of the long axis of the sUt-Hke 

 aperture coincides with that of the laterosensory canal. The lengths of the apertures in 

 our four specimens are as follows: No. I, 3 mm. on each side; No. II, 2 mm . on the right 

 side and 7 nun. on the left; No. Ill, 2 mm. on the right side and 1 mm. on the left; No. 

 IV, 3 mm. on the right side and 2 mm. on the left. The exceptionally large aperture on 

 the left side of No. II is not a slit, but an elHptical opening fully three milHmeters wide. 

 The unusually small opening on the left side of No. Ill could not be found until a bristle 

 had been inserted by way of the internal opening. It was overlooked entirely by Gudger 

 and Smith (1933) w^ho also failed to identify as a spiracular opening the exceptionally 

 large aperture on the left side of No. II, mistaking it for a perforation made by a hook. 



Each internal spiracular aperture or cavity (i.s.c.) is situated, in series with the gill- 

 sHts, between the hyomandibular cartilage and the palatoquadrate (Text-figure 82, 



