ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 963 



sharply distinguished from one another. The relation of gustatory to 

 olfactory organs is about the same, and there are all kinds of inter- 

 mediate stages between them. Much the same is true also of auditory 

 hairs. 



The ganglia which supply the sense-organs may become doubled. 

 The morphological connection between tactile setaa and glandular 

 hairs indicates a close connection between nerve-activity and the 

 secretion of material. In Anguis fragilis, he reminds us, a strong and 

 peculiar smell may be sometimes noticed, although this reptile has no 

 dermal glands. Here we are led to the conclusion that the smell 

 must arise from the goblet organs of the skin, and therefore from the 

 nervous end-organs. 



Development of various kinds of Ocelli.* — Herr J. Carriere 

 states that some of the scorpions have true rudimentary ocelli ; in 

 Chelifer the eyes are colourless, there is a thick chitinous lens, and 

 underneath it are two layers of cells, one lenticular and one retinal, 

 but there is no pigment, and there are no rods. The irregularity in 

 appearance of these organs in various genera speaks to their being 

 organs which are disappearing. 



The EphemeridaB have true eyes, but they differ much from the 

 typical ocelli of spiders, flies, or bees ; above the peculiar layer of 

 retinal cells there is a large spherical lens formed of clear chorda- 

 like cells, and the lens is most like that of the eye of Pecten. The 

 cornea lies like a watchglass above the lens, and the whole organ has 

 very much the form of the eye of a raptorial bird. 



The author has been able to study the development of the ocelli 

 of the Chrysididae and Ichneumonidaa, w r hich he thus describes : the 

 cells of the hypodermis elongate and become divided into two layers ; 

 at the periphery of the rudiment there is formed on one side a pouch- 

 like invagination, which is directed obliquely downwards, and both 

 layers take part in this ; the cells of the outer layer are those that 

 form the lens, the inner the retina. The pouch grows in under the 

 centre of the lens-like rudiment, while the cells which take no part 

 in the invagination elongate and form a ridge above the pouch, and 

 takes part in forming the corneal lens. As the pouch widens the 

 cells of the ridge pass to the sides. In the Yespidaa and Diptera the 

 process is somewhat modified, the ridge disappearing more or less. 

 Reference is made to the recently published observations of Mr. Locy 

 on the development of Agelena nsevia, and priority is allowed him as 

 to the discovery of the primary thickening and the invagination, but 

 Herr Carriere is of opinion that the later stages of the development 

 of the spider's eye resemble what he has seen himself, or that, in 

 other words, there is no constriction of the invaginated pouch, such 

 as has been described by Mr. Locy. 



* Zool. Anzeig., ix. (188G) pp. 496-500. 



3 r 2 



