Miscellaneous. • 147 



the contained soft structures. He writes, "In C7«'ton the exter- 

 nal layer, which seems to be of a delicate fibrous texture, but 

 which is of extreme density, is perforated by large canals, 

 wiiich pass down obliquely into its substance, without pene- 

 trating, however, as far as the middle layer.' ' 



My father-in-law. Dr. Gwyn Jeffreys, has pointed out to 

 me that Costa* figures what are evidently the eyes on one of 

 the intermediate shells of a very small species of Chiton 

 {To7iicia) ruhicundus. They are figured as mere black dots 

 and referred to as fine punctuations, but their arrangement is 

 correctly shown. 



The late Dr. Grayf, in his well-known paper on the struc- 

 ture of the Chitons, wrote: — " The greater number of species 

 have a part of the valve which is not covered by the mantle, 

 but exposed. This exposed part consists of a perfectly dis- 

 tinct external coat, peculiar, I believe, to the shells of this 

 family. The outer coat of these valves is separated from the 

 lower or normal portion by a small space, filled by a cellular 

 calcareous deposit, which is easily seen in a section of the 

 valves." 



I have prepared drawings illustrating the arrangement and 

 structure of the eyes and other sense-organs in the shell in 

 various genera of Chitonida?., and hope to publish them with a 

 more complete account of my results in the coming winter. 



I beg to express my best thanks to Dr. Giinther for giving 

 me every facility in making use of the British-Museum col- 

 leetiou. Dr. Woodward kindly went over the fossil Chitons 

 in the Paleeontological Department with me, but we could 

 detect no traces of eyes in any of them. This is remarkable, 

 since the ancient forms of the group appear to be allied to 

 Schizochiton. 



MISCELLANEOUS. 



On the Submaxillary in Masticating Insects. 

 By M. J. Chatin. 



The maxilla in masticating insects is supported by a basal piece 

 the functional importance of which cannot be disputed, but which 

 possesses a still greater interest from the point of view of the mor- 

 phology of the parts of the mouth and even of the appendicular 

 organs considered generally. Nevertheless it has hardly been even 

 mentioned l)y a few writers, among whom we must cite Kirby and 

 Spcnce, who gave it the name of the cardo (hinge), a term happily 

 enough representing its mode of articulation ; Erulle gave it the 

 name of submaxillary, which I here retain, so as not to introduce 

 any neologism into an exposition already full of details. 



' Fauna di Napoli : Animali molli, Chitone,' taf. iii. fig. l,e. 



J. E. Gray, " On the Structure of tlie Chitovs,'''' Phil. Trans. 1848. 



