162 BULLETIN OF THE BUREAU OF FISHERIES. 
collenchymatous and about 250 to 350 u thick. Its superficial stratum is fibrous; that is, the cells are 
elongated and rather compactly arranged parallel to the surface. From the ectosome wide tracts of 
collenchymatous tissue pass into the interior, marking out the pathways of the main canals. 
Spicules.—The megascleres (Pl. LXVI, fig. 56a toc) are styles which fall in two very distinct classes, 
although intergrades can be found. 
(1) A stouter form (fig. 56a), smooth, cylindrical, usually slightly curved; the characteristic spicule 
of the peripheral skeleton. In the upper part of the sponge this spicule generally measures 400 to 600 u 
by roto 124. Inthe lower basal part of the body it is larger, reaching 7oou by 20. The oxeate modi- 
fication sometimes occurs (fig. 566). Intermediate forms, between style and oxea, with irregular, 
imperfect ends, also occur (fig. 56c, d, e). 
The stouter form of style is present in small number in the mesial skeleton, sometimes projecting 
from the individual fibers. A short form, often bent, about 200 to 350 u by 16 to 20 uw occurs with some 
frequency. 
(2) A slender form of style 400 to 500 u by 3 to 8 uw, the commonest thickness being about 4 to 6 u, 
is the characteristic spicule of the axial (mesial) skeleton. This spicule is smooth, cylindrical, usually 
slightly curved, sometimes exhibiting more than one bend. The oxeate modification occurs. 
Skeletal framework.—The framework includes an axial portion, which, since the sponge is essentially 
lamelliform, is better designated mesial, and a peripheral portion. 
The mesial skeleton is a reticulum made up of longitudinally coursing (i. e., extending from base 
to free margin of sponge) fibers, which branch and anastomose (Pl. LXV, figs. 46 and 47). In the basal 
part of the sponge this portion of the skeleton becomes quite thick; everywhere it occupies all but the 
superficial zone of the body. The fibers are cylindrical and plurispicular, with abundant spongin; 
the spicules arranged more or less longitudinally. Common range in thickness of individual fibers, 4o 
to 100 W. 
The peripheral skeleton consists chiefly of obliquely radial fibers, into which the mesial skeleton 
is produced (figs. 46 and 47). They are slender in the marginal region of the lamella, but become thicker 
below, in the basal region becoming strong and plumose. ‘The fibers include but little spongin, only 
enough to hold the spicules together. The radial fibers branch to some extent, and at the distal end 
the spicules fray out, forming a bunch or bunches, generally divergent in character. These outermost 
spicules are embedded in spongin only at their very base. The radial fibers extend into the conuli. 
If, as often happens, the conulus is subdivided into secondary conuli, each of these receives a spicule or 
two or a bunch of spicules. 
The peripheral skeleton includes also radial megascleres, which beset the mesial skeleton on its 
outer surface, between the radial fibers. They extend out toward the surface, and are especially con- 
spicuous in the depressions between the ridges or other conulose elevations. These spicules belong to 
the stouter form of style. 
Vosmaer has recently (1912) made an attempt to establish the genera Axinella, 
Phakellia, Acanthella, and Raspailia on more definite anatomical grounds. He finds 
that a new genus, Phacanthina, must be made for Schmidt's Acanthella obtusa. 
Vosmaer finds that the species which he has studied, representing the above five 
genera, differ in definite points as to the character of the skeletal framework, and he 
therefore concludes that, in the diagnosis of the genera, the character of the framework 
should play an important part. How well the numerous species hitherto grouped under 
the above genera, when studied anatomically, will fit into the five skeletal schemes 
described by Vosmaer is, of course, a question. But there is no doubt that the distin- 
guished spongologist, whose recent death entails such a loss upon zoological science, 
should be followed in the resolve to learn more definitely about the skeletal framework 
of these sponges and to use the data in classification. 
According to Vosmaer’s generic schemata, Acanthella and Phacanthina lack the 
radial fibers (extraaxial funiculi) which are found in Axinella, Phakellia, and Raspailia. 
The Beaufort sponge would therefore fall in Phakellia. But it seems not impossible that 
