110 Prof. M'lntosh's Notes from the 



rest having them so reduced in size as to appear for the most 

 pai't smooth. Such a scale when enlarged (as in the figure* 

 alluded to by Baron de Saint-Joseph) could only be compared 

 with an anterior scale of L. clava, yet it was an average one 

 of L. Wahlbergi. Further, the minute structure of each 

 quite diverges. In L. Wahlbergi several of the anterior 

 scales are hispid, with prominent acute spines (PI. II. fig. 11), 

 the tips of which are minutely nodular, so that the surface in 

 some views presents a somewhat areolar or " scaled " appear- 

 ance, resembling that of the tissue of the scale itself, and 

 which enters the base of the spine. Moreover, the nodular 

 tip is slightly bent. On the other hand, the truncated 

 capstan-like tubercle characteristic of the first scale of L. clava 

 has its terminal " boss " minutely and somewhat regularly 

 nodular, the tip of each process having a spine (PI. II. fig. 12). 

 When viewed from above the rim of the " boss " is thus 

 minutely hispid. A glance at the respective figures in PI. II. 

 will indicate the essential differences better than any descrip- 

 tion, and they are drawn precisely to the same scale. The 

 arrangement and structure of the other papilla? on each scale 

 also diverges. It has been frequently observed that where 

 allied forms differ from each other specifically, the bristles, as 

 well as the minute structure of the scales, differ. Accordingly 

 it is found that the dorsal bristles of L. Wahlbergi have a 

 stouter tip, with a definite curve, and much less elongated 

 and tapered than in L. clava. The ventral bristles again 

 have a more elongated tip, with a longer row of spinous 

 ridges. From point to point therefore the European and 

 South-African forms diverge, even the scales in the latter 

 being distinctly smaller. 



Baron de Saint-Joseph has the credit of first publishing 

 the description of the minute structure of the anterior scales 

 of Lepidonotus clava, though the term scales (" e*cailles ") 

 applied to the hispid tips is apt to mislead. I am in doubt 

 also about their special sensory function. His figure (pi. xiii. 

 fig. 4 f) of one of the smaller processes of course differs from 

 the condition in the larger capstan-like tubercles. The 

 smaller tubercles are simply hispid, with tapering chitinous 

 spines which are proportionally larger than in the prominent 

 tubercles. 



* Ibid. pi. xviii. fig. 8. 

 t Op. cit. 



