784 KECORD OF CURRENT RESEARCHES RELATING TO 



same general manner from the optic nerve as in Cermatia, wliere tlie 

 facets are much more numerous. The eye of Cermatia is composed of 

 a hemispherical, many-facetted cornea, the lenses of which are 

 shallow, doubly convex, being quite regularly lenticular, the chitinous 

 substance being laminated as usual. Each corneal lens is underlaid 

 by a retina about as thick as the cornea, the inner surface of each 

 retinal mass being convex. Corresponding to each lens is a separate 

 mass of connective tissue, which increases in thickness from the end 

 of the optic nerve outward towards the cornea ; though the entire 

 retina of the eye extends back to the ganglion opticum. Within the 

 broad stratum of connective tissue, forming the entire retina of the 

 eye, lies next to the corneal lens a layer of " vitreous cells " or " lens- 

 epithelium " of Graber. This layer is succeeded by the series of 

 rather large visual rods, one in each mass corresponding to each 

 corneal lens ; these rods are long and sharp, conical at the end which 

 extends nearly to the inner edge of the retinal mass ; they each 

 possess a nucleus, and the connective tissue enveloping the rods is 

 nucleated, while there is an irregular layer of nucleated cells near or 

 around the ends of the rods. There are no cones ; these not being 

 yet detected in the eye of Myriapods. This layer of cells is suc- 

 ceeded by a thin, slightly curvilinear, transverse strip of connective 

 tissue passing through the entire eye, and behind it are the loose, 

 nucleated, spherical cells forming the ganglion opticum. 



The brain of Cermatia forceps, as shown by several sections, is 

 developed on the same plan as in Bothropolys, and the myriopodan 

 brain seems to correspond more closely in its general form and 

 histology with that of the insects than the Crustacea. The large, 

 thick optic nerve arises from the upper side of each hemisphere. The 

 median furrow above is deep, and on each side is a mass of small 

 ganglion cells ; also a mass in the deep fissure below the origin of 

 the optic nerve, and another mass on the inferior lobe extending 

 down each side of the cesophagus, probably near or at the origin of 

 the posterior commissure. These masses, i. e. those on the upper and 

 under side of the brain, connect on each side of the median line, and 

 in this respect the brain is as in Bothropolys. There are no large 

 ganglion cells as in Crustacea, including Limulus. 



There is, then, no very close resemblance in form or histology 

 between the eye and brain of Limulus and the Myriapods, the two 

 types of eye being essentially diiferent. 



7- Arachnida. 



New "Work on Parasites. — M. P. Mequin has just published 

 a work entitled ' Les Parasites et les Maladies Parasitaires.' The 

 part which has already appeared deals with the parasitic Arthropoda. 

 In addition to the sixty-three woodcuts which are intercalated in the 

 text, there is a separate atlas of twenty-six plates. This work ought 

 to be useful as a dictionary and handbook of the characters of the 

 more important Arthropod j^arasites, for though not without faults 

 it goes a long way to supply a want which has been long felt. 



