426 HARRIS HAWTHORNE WILDER ON 
ness, but may perhaps have given in his drawing somewhat too great regularity to the 
fenestrations. Both Huxley (Necturus) and W. K. Parker (Proteus) appear to have 
entirely overlooked the structure or at least not to have recognized its skeletal nature. 
In the adult it appears like a shell covering the dorsal half of the capsule, its edge being 
entire and running along the lateral outline. Its surface is perforated by openings in the 
form of irregular parallelograms approximately arranged in two longitudinal rows and 
converting the entire structure into a delicate cartilaginous network. At the anterior end 
a narrow loop appears to extend across the ventral side, thus enclosing the nostril. By an 
examination of the larvae it would seem that this structure at first consists of a single 
longitudinal rod applied to the inner side of the capsule, after which transverse rods 
develop between the folds of the nasal mucous membrane. Miss Platt (97) has given a 
brief description of this in a larva of 46 mm., and Winslow (98) has both described and 
figured it at the same stage. In the printed description of both authors the transverse 
lateral processes develop or project directly from the main longitudinal rod, but in Win- 
slow’s figure 16 certain of the transverse rods appear entirely separate from the longi- 
tudinal one as though they had arisen independently of it. The later development of this 
capsule and the manner in which the original elements finally weave themselves into the 
complicated network seen in the adult, are points which have not as yet been investigated. 
The term “optic capsule” seems almost too formal a word for the thin cartilaginous 
ring which appears in the sclera and surrounds the eye. It is hardly demonstrable to the 
unaided eye but is clearly seen in sections. Miss Platt found it in a larva of 46 mm. to 
be “ three cells wide and one cell deep,” and in a small adult, of which I have sections, it 
is from about 15 to 20 cells wide and about 4 cells deep in the thickest portion, tapering 
towards each edge. The drawing of it given in plate 64, figure 6, is purely diagrammatic 
and obtained from sections, as I have not succeeded in preparing an eye so that it could be 
seen directly. According to Miss Platt, both nasal and optic capsules arise independently. 
The Teeth. 
The teeth of Necturus are arranged in two parallel rows in the upper jaw and in a 
single row in the lower, those of the latter fitting into the interval between the two rows 
of the former, their mutual arrangement being such that the teeth on the dentale oppose 
those of the vomer, those on the spleniale oppose those on the palato-pterygoid, while the 
premaxillary teeth form an unbroken outer row shutting over all the rest. At the junc- 
ture between the vomerine and palato-pterygoid teeth of the inner, upper row, and again 
between the dental and splenial teeth of the lower row there are slight breaks in the con- 
tinuity of the rows, and usually a perceptible diastema or gap. Several of the authors 
