308 Prof. J. Wood- Mason on a new Genus o/'Mantidse. 



The chewing-apparatus might be said to consist of a great 

 number of teeth of various sizes. The lowest ones, five in 

 number, one above another, are very much larger than the 

 rest ; above these are two, side bj side, about half the size 

 of the preceding, which' are the commencement of the two 

 series which bound the cluster of minute teeth (tooth-papillse) 

 on either side ; [and they gradually diminish in size upward. 

 The teeth or papillae between these series are very small and 

 arranged above in four vertical rows, then lower down in 

 three and two series, and gradually diminish downwards 

 within the mouth to a single papilla. The mouth-papillse 

 are very small indeed, short, cylindrical, and vary from three 

 to five on each side of each of the five mouth-angles or tooth- 

 columns. They are hardly distinguishable from the tooth- 

 papillge, as they are situated close together near the apex of 

 the column. 



EXPLANATION OF PLATE XV. 



Fig. 1. Upper surface, of natural size. 



Fig. 2. Lower sm-face. 



Fig. 3. Part of underside of an arm, enlarged. 



Fig. 4. Part of upperside. 



Fig. 5. A Madreporic shield : b, c, two forms of oral shields. 



XXVII. — The Y Sites Ashmolianus of Westioood, the Type of a 

 new Genus ofMantidae. By Prof. J. Wood-Mason. 



^THALOCHROA, gen. nov. 



^ ? . Sexes alike. Body greatly elongated, linear. Head 

 small, rather higher than broad; vertex of considerable an- 

 tero-posterior extent, its lateral lobes produced into a conoidal 

 boss behind each eye, the central division of its median lobe 

 with a low transversely convex elevation (answering to the 

 well-developed process seen in Blepharis and Phyllocrania) 

 ending abruptly over the ocelli ; eyes much as in Blepharis 

 mendica^ but not quite so forwardly projecting ; ocelli slightly 

 oval, conspicuous, prominent, mounted on short pillars, in the 

 male distinctly differentiated into pupil and iris ; facial shield 

 broader than high, pentagonal, inclining to be trefoil-shaped, 

 its upper margin slightly produced to a projecting point in the 

 middle, with a faint ridge on each side near and parallel to 

 the lateral margins ; " chaperon " strongly transversely cari- 

 nate. Antennas short and setaceous. Prothorax greatly elon- 



