markings and attitudes of lepidopterotia larvte. 299 



withdrawal of the anterior part of the body became more 

 complete, the attitude acquired an entirely new signi- 

 ficance when the sudden swelling of the segments 

 became a source of terror to enemies. After this the 

 course taken must have been that described by Weismann. 

 I do not think that M. stellatarum has yet reached the 

 point at which terror is caused by its attitude. The 

 white shagreen dots are terminated by minute and 

 simple hairs, and the relation of the larval markings to 

 the shagreen dots is exactly similar to that described in 

 6'. occllatas, &c. Anteriorly the subdorsal consists of a 

 linear series of enlarged dots only ; posteriorly the effect 

 of the dots is heightened by a whitening of the ground 

 colour. These two conditions gradually shade into each 

 other. Above the line there are no dots upon the 

 shading of darkened ground colour. The subspiracular 

 line has no doubt a similar history, but it does not show 

 the whole origin in its different parts as is the case with 

 the subdorsal. The shagreen dots upon the horn are 

 black. 



6. The origin of shagreen dots in Sphingid^. — 

 This is rendered apparent by an examination of a larva 

 of S. liriustri or S. ocellutus in the first stage. In 

 both species the dots are terminated by hairs which are 

 of considerable length ; they are hairy larvae with 

 tubercles at the base of the hairs. In later stages the 

 tubercles are alone apparent to the naked eye, but the 

 use of a lens at once shows that a rudimentary hair is 

 present upon the summit of each, and this remains true 

 throughout the ontogeny. This explanation holds good 

 for all shagreened Spliinx larvae yet examined from this 

 point of view (the genera Smerinthus, Sphinx, and Macro- 

 glossa), and there can be no doubt about the validity of 

 this interpretation of the shagreen dots of SpJiingidce. 

 Shagreen dots are the persistent tubercles at the bases 

 of hairs which have become so shortened as to escape 

 notice. 



Weismann mentions the presence of small warts, each 

 emitting a single bristle, upon the larva of Dcilephila 

 euphorhicB in the first stage (page 202 of the English 

 translation of his Essay on the markings of Caterpillars, 

 &c.). Although these warts must be the origin of the 

 shagreen dots in this species, Weismann does not take 

 such a view, for he describes the independent origin of 



