78 BULLETIN OF THE 



internal limiting membrane ; the inner reticular layer (called by him 

 the neurospongium), and scattered in this the ganglion cells ; the inner 

 nuclear layer (called by him the ganglion retinae) ; the rudiments of 

 the rods and cones ; and the radial fibres. Krause's remarks on the eye 

 of Myxine are interesting. He ('86, p. 19) says: "Sein Auge wurde 

 zu den perotischen riickgebildeteu, wie das von Proteus anguineus 

 zu rechnen sein, und man kann die rudimentar entwickelte Retina 

 deshalb nicht zur Construction phylogenetisches Aufbauten benutzen." 

 It appears to me that the most interesting fact concerning the Myxi- 

 noid eye, at least from a comparative point of view, is the entire ab- 

 sence of pigment in it. I may here say that I have made some sections 

 of the eye of a member of this family found at Monterey, Cal., and 

 named by Lockington ('78, p. 793) Bdellostoma stontii, and can con- 

 firm the statements made on this point by all other observers. I have 

 so far found no trace of pigment in the eye. The proximal layer of 

 the primitive optic vesicle remains distinctly cellular throughout life, 

 as always stated, but no pigment appeal's either in it or in the meso- 

 dermal tissue immediately surrounding the eye. If, as seems certain 

 with the rudimentary eyes of the three forms that we have been consid- 

 ering, an increase of pigment is an incident to the gradual diminution in 

 functional importance and structural completeness, I can see no very 

 satisfactory explanation for the absence of pigment in the Mj^xinoid eye, 

 if we are to suppose, as I take it for granted we must, that it too is 

 the result of arrested development. 



Wyman ('54, p. 395; '54% p. 18; see also Putnam, '72, pp. 18, 19) 

 has made us acquainted with the eye of Amblyopsis spelseus as far as he 

 was able to with the methods of morphological investigation of his time. 

 And it is altogether probable that all he has made known concerning 

 this species holds good for Typhlichthys subterraneus, since the two 

 forms are so nearly alike that systematists are not fully agreed that 

 they should be considered as separate species. 



According to Wyman, the eye of Amblyopsis has "a sclerotic coat, 

 a choroid coat, a layer resembling the retina, a lens, and a nerve." 

 His notes, published by Professor Putnam, give somewhat more of de- 

 tail as to the structui*e of these several parts. He says : " Under the 

 microscope, with a power of about twenty diameters, the following parts 

 are satisfactorily made out : ... 2d, a layer of pigment cells for the 

 most part of a hexagonal form, and which were most abundant about 

 the anterior part of the eye ; 3d, beneath the pigment a single layer 

 of colorless cells, larger than a pigment cell, and each cell having a 



