of the Mole-cricket, 407 



tion the insect from time to time dresses, if I may use the ex- 

 pression, its palpi ; bending them inwards and brushing the 

 surface of their extreme parts by a frequent application of the 

 maxillge. A similar care of the antennae and palpi is observable 

 in the Gri/llus viridlssimus; with the additional circumstance, 

 that that insect very often passes between its maxillae the cu- 

 riously padded surfaces of its feet, much in the same manner 

 as a cat licks its paws. 



The ej/es*. — The gryllotalpa has two compound eyes, as 

 they aie called, and two ocelli or stemmata. Latreille uses 

 this expression ^'ocellus medius siihohiteratiis ;'' from which it 

 may be inferred that he supposes the ocelli to be three in num- 

 ber ; but after the most careful examination I have not been 

 able to discover more than two. The compound eyes are si- 

 tuated immediately behind, but a little exteriorly to the an- 

 tennae : the corneae of these eyes, which are large in propor- 

 tion to the size of the head, are segments of a sphere, flattened 

 however on the inner side so as to present a vertical plane 

 surface to a similar plane surface in the opposite eye ; and it 

 is remarkable that this part of the cornea, and the mere mar- 

 gin of the rest of it, are the only parts capable of freely trans- 

 mitting light : all the remaining portion is covered, on the in- 

 terior surface, by an opaque pulpy membrane, or pigments of 

 a mulberry-colour ; yet the portion obstructed by this pigment 

 is in itself nearly as transparent as flint-glass ; it is studded 

 over on the interior surface with numerous depressions of a 

 circular form, which, being very closely set together, give it a 

 reticulated appearance. 



The stemmata are placed between the middle of the com- 

 pound eyes, so as to be rather further from each other than 

 from the eye of the same side. They are not so lai-^e as a 

 very minute pin's head, of a lenticular form, perfectly trans- 

 parent, but not quite colourless, resembling particles of very 

 pale cairngorum quartz. In two instances 1 have found only 

 one of the stemmata, without any trace of the other. An 

 anomaly somewhat of the same kind has been observed by the 

 father of my friend Dr. Ogle, of this university, in the case of 

 a man ; on one side of whose breast the usual rudiments of a 

 mamma were entirely wanting. 



With respect to the small quantity of light admissible 

 through the corneae of the eyes of the mole-cricket, it is ap- 

 parently sufficient for the purposes of an animal living almost 

 constantly underground. The spherical form of that part of 

 the corneae which is itself incapable of transmittuig lirrht is 

 probably intended, (as was suggested to me by Mr. Wliessel, 

 * Vide Plate II. figs, 1 ami 2. 



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