288 



Bashford Dean hiemorial Volume 



Text-figure 18 

 Scales (x5) from the 

 lateral line region of the 

 tail of Chlarnydoseldchus. 

 Note the elongate scales 

 which partly cover the 

 open lateral line canal. 

 After Garman, 1885.2. 



Elasmobranchs in general, Garman goes more into detail. However, 

 it does not seem necessary for us to review his description further 

 than to say that in adult fish the canal is a well-marked open 

 groove extending from the head along each side of the body above 

 a crease marking the dorsal limit of the body-cavity (our Figure 

 5, plate II). On the tail, the canal runs along the lateral surface 

 far out on the caudal fin, as may be seen in any of the figures of 

 the entire animal reproduced herein. On our embryos it extends 

 clear to the tip of the tail. 



Observations have been made on certain curious deviations 

 from the normal course of the lateral line canal. Thus Garman 

 (1887, p. 267) writes of his second fish that "the lateral line, with 

 a few short breaks posteriorly, continued to within an inch of the 

 end of the tail." Mrs. Hawkes (1906, p. 964) notes that "In all the 

 specimens examined there is a tendency in the region of the dorsal 

 fin to a departure from a straight Hne. In two specimens this 

 tendency produced four distinct undulations. ... In other cases 

 the canal undulated slightly. No explanation of this phenomenon 



can be offered. This same region had on one side, in one specimen, a complete break of 



5 mm." Mrs. Hawkes' illustration showing deviations from a straight line is reproduced 



herein as our Text-figure 19. These sinuosities are also noted by Garman (1899, p. 44) for 



his specimens. One of these had on one side "just above the forward end of the caudal" 



just such an irregularity as that figured by Mrs. Hawkes. Of one of his specimens. 



Dean wrote in his notebook: "In a small female Chlamydoselachus, July, the right lateral 



line was divided for a distance," and then follows a rough diagram showing the parallel 



doubling. 



To these may be added the following observations on our three adult female fish. 



On the right side of No. I, about 50 mm. 



behind the point of the pectoral, the 



lateral line loops down onto the flank for 



a distance of 30 mm., and on the base of 



the tail are sinuosities for a distance of 



125 mm. On the left side there is a 



marked looping downward just anterior 



to the middle point of the body proper, 



and there are also some sinuosities under 



the base of the dorsal. For fish No. II, 



we note nothing unusual on the right 



side, but on the left the lateral line curves 



upward under the tip of the caudal. In 



our largest and best-preserved fish (No. 



Text-figure 19 



Variations in the lateral line canals of Chhynydoselachus. 



The solid line shows those on the left side, the dotted 



one those on the right. 



After Hawkes, 1906. 



