86 EXTRACTS AND ABSTRACTS FROM FOREIGN JOURNALS. 



orly to the facets. Galathea strigosa, Astacus fluviatilis, and Astacus 

 marinus, shew the same structure. In Galathea, the substance between 

 the cornea and crystalline bodies is thinner, and the masses appended 

 to the posterior portions of the latter are shorter than ordinary. 

 In Astacus fluviatilis, a delicate margin exists around the crystalline 

 bodies, and no tube could be discovered within the nervous cord. In 

 Astacus marinus, the transparent masses behind the bodies are very 

 long ; whilst in Pasiphcea squinado and Palinurus locusta, none could be 

 found. In Squilla mantis, the nervous fibril has a brown coloured 

 sheath, and is dilated anteriorly. In all the Coleoptera which were 

 examined, as in Melol&ntha vulgaris, M. fullo, Dytiscus marginalis, 

 Staphylinus erythropterus, Calosoma sycophanta, and Cetonia aurata, the 

 crystalline bodies are conical, and appear, with the exception of Cetonia 

 aurata, to lie immediately upon the cornea. The transparent masses 

 behind these bodies are also wanting. By gentle pressure, the crystalline 

 cones split into an indefinite number of prisms, and have a narrow 

 margin, which is probably caused by the presence of an envelope or 

 case. In Melolontha vulgaris, Cetonia aurata, and Calosoma sycophanta, 

 at the points, a small granule was seen, which probably belongs to the 

 optic nerves. The nervous fibril is thicker (in Cetonia aurata, three or 

 four times thicker) at the place where it is given off by the ganglia 

 than the rest of the nervous cord ; and in this species the bason-shaped 

 expansion before alluded to, reaches to the facets, and the cones are 

 surrounded with much pigment. In the Orthoptora the crystalline 

 bodies are also conical, and the optic nerve has a dark tube in the cen- 

 tre. The pigment, like in the Coleoptera, leaves round openings in the 

 cornea, free of any. In Gryllotalpa, the crystalline bodies imbedded in 

 the dark-brown pigment are very small ; and in Locusta viridissima, 

 their basal surfaces have an hexagonal-form, with blunt points, and the 

 nervous fibril has a clear tube within it. Mantis religiosa has very long 

 hexangular crystalline bodies immediately beneath the cornea and very 

 closely packed together, their points alone being provided with pig- 

 ment ; the bason- shaped expansion of the nervous fibril, which latter 

 possesses a sheath and clear tube, is green. In the Hymenoptera, 

 Vespa crabro has a thin transparant membrane next the cornea, which has 

 divisions equal in number to the facets of the cornea, and which keeps 

 the crystalline bodies connected together when separated from this lat- 

 ter covering. The bases of these conical bodies are placed in hexagonal 

 divisions of bright yellow pigment. The comparatively very thick but 

 uniformly cylindrical nervous fibril has everywhere dark pigment, and 

 is provided with a delicate and clear tube ; the latter, with the pig- 

 ment belonging to it, ceases at the point of the cone. The inner tube 

 surrounds the cone in a bason-like manner. Apis mellijica has also 

 short conical bodies, with slightly convex bases enveloped in dark red 

 pigment ; its nervous fibre is similar to that of Vespa. Bombus is the 

 same. 



(To be continued.} 



