150 PANTOPODA. 



any great stress upon this point. A tolerably large spine, 

 comparable with that on the first limb, also occurs on the two 

 following limbs (Fig. 69). That on the first extremity, however, 

 is distinguished, from the others by having at its point the aperture 

 of a gland (dr). The fine filaments which can be produced through 

 this aperture serve for attaching those larvae which, after quitting 

 the egg-envelope and undergoing the first moult, fix themselves on 

 the ovigerous limbs of the male. The second and third pairs of 

 limbs possess hooks only (Fig. 69, 77. and 777.). The muscles 

 of all the limbs, especially the first, are well developed. Whereas 

 the first are used for fixation, and especially for prehension, the two 

 posterior pairs are used for crawling and climbing. These larvae 

 live among algae, Hydroids, etc. 



Another feature of the external organisation of these larvae is 

 the proboscis, or beak, which arises as a ventral conical outgrowth 

 between the bases of the anterior limbs (Fig. 69, s). At its tip 

 lies the oral aperture. 



It appears as if the proboscis arose near the stomodaeum as an ectodermal 

 outgrowth, although some have been inclined to attribute its origin to fusion 

 of the upper lip with a pair of limbs (Adlekz). It is impossible to decide 

 whether we are justified in comparing it to the provisional proboscis of Chelifer> 

 which it cannot fail to recall, on account of the slightness of our knowledge of 

 this latter organ. 



The intestine is already provided with outgrowths, the anterior 

 pair of which are beginning to extend into the first pair of limbs 

 (Fig. 69). From the intestine, fibres of connective tissue extend to 

 the body-wall. The anus does not yet seem to be present (Dohrn), 

 and no doubt does not appear until later with the rudiment of the 

 abdomen (Fig. 71 B). 



The nervous system of the larva consists of the supra-oesophageal 

 ganglion and only two pairs of ganglia on the ventral side. Im- 

 mediately above the supra-oesophageal ganglion lie the two eyes 

 in close contact (Fig. 69). The manner in which these arise is of 

 special interest, as it appears to offer a further point of agreement 

 with the Arachnida. 



The eyes, like the nervous system, attain full development during 

 metamorphosis. The two eyes of the former stage are now joined 

 by another pair. So as to understand how these develop we shall 

 have to explain briefly the structure of the Pantopodan eye, which 

 is as yet very insufficiently understood. These eyes, like those of 

 the Araneae, consist of a corneal lens, a subjacent hypodermis 



