2o6 



HA RD WICKE'S S CIENCE- G OSS IF. 



possessed by animals widely separated in the scheme 

 of classification ; thus we find two groups of pyrami- 

 dally formed teeth, which strongly presents the char- 

 acter of fish teeth in outward form, and four regions 

 covered with minute plates, which readily recall the 

 gastric teeth in some species of Coleoptera. 



Taking the teeth first, we find two groups each 

 consisting of four teeth, having a broad base and termi- 

 nating in a sharp point ; one is largely developed, 

 two of intermediate size and one very small, the base 

 of each appears of a light colour, which indicates 

 a thin structure, while about half the length of each 



teeth two are large, and in the natural position of the 

 mouth occupy the front portion ; the other two are 

 smaller, and are situate at the back part of the oral 

 aperture. They each consist of an accumulation of 

 small plates of chitin, arranged like tiles on a roof. 

 If viewed with a low power they look like small 

 spines, but when an enlargment of five or six hundred 

 diameters is adopted, it will be seen they are tolerably 

 broad at the base and terminate in fine points. They 

 are light amber in colour and unitedly cover a large 

 surface of the mouth. 



There is also another organ, somewhat sickle- 



Fig. 145. — Teeth of Caricea tig7-ina. X 200 diam. 



tooth towards the apex is exceedingly dark, and points 

 to a thickening of the organ. 



It will be remembered that in former notes of 

 this series attention was drawn to the folding of 

 the membrane forming the tooth as it approached 

 the point of attachment ; in the present instance 

 this order is reversed, the basal portion appears 

 delicate, and at about one-third of the entire length 

 of the tooth the fold takes its rise, and is continued 

 to the apex, thus giving this part of the organ a great 

 consistency and power of attrition. 



Of the four regions bearing the similarity to gastric 



shaped (not shown in the illustration) capable of 

 protrusion and retraction ; it is by the action of this 

 part operating against the dental organs that the 

 creature seizes, crushes, and triturates its food. 



It should also be noted that the pseudo-tracheae are 

 few in number and insignificant in size. 



The perpetuation of the species is provided for by 

 the extrusion of perfect larvae about one-tenth of an 

 inch long, and, judging by their mouth organs, they are 

 powerful agents in the work of destruction of the roots 

 of plants, on which it is presumed they feed. 



Cardiff. 



