A Sphincfozoan Calcispoiiye. — Clayke. 380 
to another of tlie interseptal chambers or intersecting other 
diaphragms. The presence of this structure, when well de- 
veloped, has suggested to Waagen and Wentzel the possibility 
of a relationship to the corals and that the Pharetrones are 
actual)}' more highly organized than the true sponges, and form 
a transitional phase between the Spoiif/i.ozoa and the corals. 
We may observe that of the sphinctozoans discussed by 
Steinmann, the majority of the genera are from Mesozoic fau- 
nas. All the paleozoic genera known are from the upper Car- 
boniferous rocks of the Asturias, the Salt-Range, and now from 
Nebraska, and bear the names, Sollasla, Steinm., Ainbhjsi- 
jihonella, Sjeinm., and Sebaiujatfid, Steinm. 
The bodies from Nehawka and Weeping Water are sim- 
ple subcylindrical individuals, straight or gently (uirved, the 
largest fragment measuring 70'"'", and indicating an entire 
length not exceeding 100""". The fossils are from a calcare- 
ous shale and have, for the most part, been somewhat com- 
pressed. Their interior cavities, the cloaca and the intersep- 
tal chambers, are tilled with compact grey limestone distinct- 
ly and finely oolitic, and their exteriors are frequently entan- 
gled with encrusting br>'ozoa and remains of other fossils. 
The septate or annulate aspect of the exterior is always 
shown, and when this external surface is free of other organic 
rr^nains and cleansed of the attached matrix, it presents the 
aspect of a Fisttiliporn or of a small celled Alceolifes; that is, 
the mesh-work of the skeleton is made up of polygonal cells, 
all of small size, not always opening directly outward, but in 
))laces frequently presenting oblique apertures. So line is this 
superficial network, and so uniform the size of the cells that 
one might casually interpret the entire fossil as a macerated 
Orthoceras overgrown with an encrusting bryozoan. 
One of the specimens is preserved with its aperture entire, 
which shows it to have been a simple, narrow circular cavitj^. 
On cutting these bodies along their longer axis we observe, 
first, a continuous central cloaca, relatively much wider than 
would be the siphon of an orthoceran of the same size, but 
slightly' constricted at intervals, where its walls meet the sep- 
ta. This cloaca is delimited b}' a well-defined circular wall, 
and thus has no communication with the septal chambers or 
the cavities of the annuli, except through the perforations in 
