506 Lieut.-Col. Godwin-Austen and Col. Beddome on 



larval stage is lower and lower in embryonic level, suggests 

 that the larval stage results from an attendant retrograde 

 embryonic change to a line parallel with the Myriapod, and 

 beyond to the memberless condition of a worm. The 

 principle appears to be a general one among animals, and 

 thence the higher the species the longer the stage of youth. 



The relations in body-segments and limbs between the 

 classes of Crustaceans, Limuloids, Arachnids, Myriapods, and 

 Insects are shown in the table (p. 505). The segments of 

 the body are numbered along the left margin ; the zero oppo- 

 site signifies that the segment, though present, has no 

 appendage. 



In this table the following abbreviations are used: — Ant., 

 antenna ; App., ])aiis of jointed appendages, either pediforin 

 or branchial; M., mandible ; Mx., maxilla ; P., feet; M-P., 

 feet that serve also as jaws; Mx. & L. (under Insects), 

 maxilla? and labium ; Fol. P., foliaceous or lamellar feet or 

 appendages. 



Under the Limuloids the genus Eurypterus fails of an- 

 tenna?, but they are present in Pterygotus and are chelate ; 

 and tliis chelate (or thumb-and-finger) form characterizes also 

 the modern Limulus, the Scorpions, and the common Spiders. 

 In the table the two pairs of maxillfe of Insects are assumed 

 to belong to a single body-segment, as held by many zoolo- 

 gists, including (as he himself informs the writer) Prof. S. I. 

 Smith ; the table shows that, with this admission, the thorax 

 and head of an Insect are essentially homologous with the 

 head of a Tetradecapod Crustacean. 



LVII. — New Species of Cyclophorus and (t Siiiraculum/rom 

 the Khasi and Naga IJil/s, Assam. By Lieut. -Uol. II. H. 

 Godwin-Austen, F.R.S. &c., and Col. K. Beddome, 

 F.L.S. &c. 



Cyclophorus Muspratti, sp. n. 



Shell umbilicatcd, turbinate, slightly keeled ; sculpture, 

 apex smooth, the whorls thence arc longitudinally ribbed and 

 striated, increasing in strength near the suture from above 

 downwards, and crossed by the lines of growth, producing a 

 decussate surface; this is coarser and rougher on the last 

 whorl and under surface. Colour madder-brown, crossed by 

 mottled broken white lines on whorls 3 and -1. Spire conic, 



