320 MYRIAPODA. 



the reach of scepticism. If the reader will compare the figure of Peripatus 

 with that of an embryo Scorpion (fig. 196 A) or Spider (fig. 200 C) or better 

 still with Metschnikoffs figure of Geophilus (No. 399) PI. xxi. fig. 11, he 

 will be satisfied on this point. 



The homologies of the anterior appendages are not very easy 

 to determine ; but since there does not appear to me to be suffi- 

 cient evidence to shew that any of the anterior appendages have 

 become aborted, the first post-oral appendages embedded in the 

 lips may provisionally be regarded as equivalent to the mandibles, 

 and the oral papillae to the first pair of maxillae, etc. Moseley is 

 somewhat doubtful about the homologies of the appendages, 

 and hesitates between considering the oral papillae as equiva- 

 lent to the second pair of maxillae (on account of their con- 

 taining the openings of the mucous glands, which he compares with 

 the spinning glands of caterpillars), or to the poison claws (fourth post- 

 oral appendages) of the Chilopoda (on account of the poison-glands 

 which he thinks may be homologous with the mucous glands). 



The arguments for either of these views do not appear to me con- 

 clusive. There are glands opening into various anterior appendages in 

 the Tracheata, such as the poison glands in the Chelicerse (mandibles) of 

 Spiders, and there is some evidence in Insects for the existence of a gland 

 belonging to the first .pair of maxillfe, which might be compared with the 

 mucous gland of Peripatus. For reasons already stated I do not regard 

 the processes of the cephalic lobes, which form the lips, as a pair of true 

 appendages. 



BIBLIOGRAPHY. 



(396) H. N. Moseley. "On the Structure and Development of Peripatus ca- 

 pensis." Phil. Trans. Vol. 164, 1874. 



MYRIAPODA 1 . 



Chilognatha. The first stages in the development of the Chilo- 

 gnatha have been investigated by Metschnikoff and Stecker, but their 

 accounts are so contradictory as hardly to admit of reconciliation. 



According to Metschnikoff, by whom the following four species 

 have been investigated, viz., Strongylosoma Guerinii, Polydesmus 

 complanatus, Polyxenus lagurus, and Julus Moneletei, the segmenta- 

 tion is at first regular and complete, but, when the segments are still 

 fairly large, the regular segmentation is supplemented by the appear- 

 ance of a number of small cells at various points on the surface, which 

 in time give rise to a continuous blastoderm. 



The blastoderm becomes thickened on the ventral surface, and ?o 

 forms a ventral plate 2 . 



The classification of the Myriapo'ia employed in the present section is 



I. Chilognatha. (Millipedes.) 

 II. Chilopoda. (Centipedes.) 



2 Stecker's (No. 400) observations were made on the eggs of Julus fasciatus, Julus 

 foetidus, Craspedosoma marmoratum. Polydesmus complanatus, and Strongylosoma 



