158 PANTOPODA. 



In carrying further these attempts to homologise the limbs, this last 

 assumption leads to certain difficulties as to the position of those now under 

 consideration. A careful examination of the various views held on this subject, 

 which are all more or less speculative, would lead us too far, but we must draw 

 attention to the fact that the ovigerous limbs have by some been regarded not 

 as independent limbs, but as belonging to the second limb. Schimkewitsch, 

 who adopted this view (Nos. 14 and 15), in defending it laid weight on the fact 

 that the rudiments of the pedipalps in the embryos of the Araneae are biramose 

 (pp. 52 and 112). Each of the branches is said to give rise to a limb. This 

 view is not supported by ontogeny, since, in the Pantopodan larva, the second 

 and third limbs arise quite separately. Just as little does ontogeny support the 

 view that the tripartite proboscis of the Pantopoda arises through the fusion 

 of a pair of limbs with an (unpaired) upper lip. A third pair of limbs would 

 then be added, for it cannot be assumed that the paired pieces are merely parts 

 of one limb. The loss of two pairs of limbs by the Arachnida has even been 

 suggested (Croneberg, p. 111). The ontogeny of the Pantopoda seems to show 

 that the beak is, as Dohrn assumes, only an outgrowth of the lips of the 

 stomodaeum. The number of the ganglia corresponds to that of the limbs, 

 Adlerz, indeed, finds (in the adult), besides the ganglia of the second and 

 third limbs, another pair which innervates the proboscis. A final decision on 

 this point will only be possible when the ontogenetic conditions are clearly 

 established. 



The first limb is innervated from the brain, while the second and third limbs 

 receive their nerves from the first and second ventral ganglia. It would be of 

 the greatest importance to make certain whether an originally post-oral ganglion 

 unites with the brain, as in the Crustacea and the Arachnida. If this is not the 

 case, the limbs lost in the Arachnida must be considered to be the first limbs 

 of the Pantopoda, and their homologues must be sought in the conjectural 

 rostral limbs of the Arachnida. It does not, however, seem probable that the 

 first chelate limbs should be true antennae, and consequently not comparable 

 to the chelicerae of the Arachnida. 



We have already several times pointed out various resemblances 

 between the development of the Pantopoda and that of the Arach- 

 nida, but these do not appear to us sufficient to lead to further 

 conclusions as to the relationship of the two groups. Morgan, 

 chiefly on account of his ontogenetic researches, has recently spoken 

 in favour of such a relationship. It appears to us that, in taking 

 up this position, he was largely influenced by the structure of the 

 Pantopodan eyes. But Claus has recently shown (Vol. ii., p. 167, 

 and Vol. iii., p. 115) that the median eyes of the Crustacea also 

 arise by invagination, and that their component parts apparently 

 have the same position as those of the Pantopodan eyes (No. 2), 

 so that in this character there is similarity to the Crustacea just as 

 much as to the Arachnida. 



In assuming the loss of an anterior limb, we are obliged to shift 

 back any connection between the Pantopoda and the Arachnida to 

 very early times in the history of the Arthropoda, before the 



