The Anatomy of Chlamydoselachus 409 



In my best'preserved specimen, No. I, there are 44 coils of the spiral valve. In the 

 nine anterior coils, the angle is very acute and the cones point cephalad; in the remaining 

 coils the cones point acutely caudad. The transition between the two conditions is 

 abrupt. In specimen No. II there are 45 coils; each of these makes an acute angle with 

 the wall of the intestine, and points caudad. In specimen No. Ill there are 37 coils. In 

 the anterior third, the coils or cones are obtuse but point definitely cephalad; those of 

 the posterior third are acute and point caudad; while those in the middle third are 

 apparently transverse, but this region is much distended and is poorly preserved. In 

 this specimen the transitions between the regions described are gradual. 



Giinther's (1887) Fig. 5, pi. LXV (my Figure 15, plate IV) shows 35 coils in the 

 spiral valve of Chlamydoselachus. Of these, the first 19 point forward, one is transverse, 

 and the remaining 15 point backward. CoUett (1897, p- 13) states that in his specimen 

 "the intestine (colon) is cylindrical, very muscular, and contains 47 spiral valves." In 

 a specimen described by Hawkes (1907) there are 43 coils : the first 7 (my Text'figure 73) 

 point forward, one is contorted, and the remaining 35 are directed backward. Hawkes 

 points out that the inclination of the spiral valve has a physiological significance : where 

 the valve is directed forward the passage of the food is undoubtedly slower than where 

 it is directed backward. 



In Heptanchus maculatus (Daniel, 1934, Fig. 123 and pp. 124-125) the spiral valve 

 makes 17 or 18 turns. The folds are far apart anteriorly and very much closer posteriorly. 

 The valve is considerably broader than the diameter of the intestine and is thrown into 

 a series of cones having their apices pointed anteriorly. The surface of the valve, viewed 

 under the microscope, shows numerous finger^like villi. 



It has been noted in Chlamydoselachus that the anterior coils of the spiral valve 

 usually point forward, and the posterior coils usually point backward. This condition 

 of the spiral valve seems to be exceptional among elasmobranchs. A similar condition 

 has been found (Parker, 1885) in a single specimen of Scyllium canicula, and something 

 like it occurs in Zygaena (Parker, 1885, Fig. 8, pi. XI). In most sharks the apices of prac' 

 tically all the coils point forward, as in Scyllium (Parker, 1885, Fig. 5, pi. XI); or backward, 

 as in Heptrayichias perlo (Garman, 1913, Fig. 1, pi. 58). In some specimens of Raja (Parker, 

 1885) the apices of all the coils point forward, while in other specimens all but the first 

 coil are deflected backward. Moreover in some sharks, as in Cephaloscyllium umhratile 

 (Garman, 1913, Fig. 2, pi. 58), and in some specimens of Raja (Parker, 1885), an axial 

 cord extends the entire length of the valvular intestine. In other sharks, as in Isurus 

 punctatus (Garman, 1913, Fig. 3, pi. 58), and in other specimens of Raja (Parker, 1885), 

 there is instead an axial tube. Both axial cord and axial tube occur, in Chlamydoselachus, 

 in each individual specimen, where they are restricted to different parts of the valvular 

 intestine. Thus in the valvular intestine of Chlamydoselachus there are combinations of 

 features that almost always occur separately in other elasmobranchs. This affords 

 a striking example of the structural comprehensiveness usually considered characteristic 

 of the more archaic members of a phylum or class. 



