324 WILSON. [Vou. IX. 
neben den Doppelkeulchen mit glatten Kopfen solche, wo auf 
dem Scheitel des Kopfes einige kleine Knotchen entstehen. 
Diese letztere Form nimmt in einzelnen Individuen iiberhand, 
und ist in noch anderen ausschliesslich vorhanden.” All the 
individuals of Tedania B. examined agreed in this respect, and 
it seems proper here to regard the nicked head as a specific 
characteristic. Tylotes are found free and scattered about in 
the gelatinous tissue. Round the subdermal cavities of this 
tissue they form loose bundles which follow the curves of the 
cavities, Pl. XIX, Fig.61. The brushes of tylotes which support 
the dermal membrane have mixed with them a number of 
microscleres (oxeas). Crossing the meshwork of spicules and 
pursuing an entirely independent course, are found here and 
there a few long and slender skeletal bundles consisting largely 
of tylotes intermingled with oxeas. The oxea, Pl. XX, Fig. 674, 
aside from the situations just spoken of, is found in abundance 
in the gelatinous tracts where it varies in size, as has been 
mentioned, from the dimensions figured to those of a micro- 
sclere, the latter form being especially common round the 
walls of the larger efferent canals. The skeletal meshwork is 
made up exclusively of strongyloxeas, which are all as is shown 
in Fig. 67a, slightly bent. I have spoken of this meshwork 
as confused, Its ‘contusedyim ithe first place becausesthe 
spicules are so closely packed, that the meshes are not bounded 
by single spicules but by little bundles. And in many places 
it so happens that the spicules are arranged in such a way that 
they both bound the meshes and help to form a continuous 
skeletal bundle. Two such bundles are shown in Fig. 61, 
which fairly well represents the meshwork of spicules. 
The homology between pores and oscula upheld by Barrois 
(I) and others, receives perhaps some additional support from 
the occurrence in Tedania of such openings as those shown in 
Pl. XX, Fig. 68 (a small portion of the surface). These open- 
ings lie in the gelatinous furrows, and in their immediate neigh- 
borhood there are but few pores. They are larger than the 
pores, but very much smaller than the ordinary oscula, and may 
therefore be classified as structures intermediate between the 
two. 
