74 THE PALEONTOLOGY OF MINNESOTA. 
{Anomalospongla 
occur in Silurian strata near Edinburg, Scotland.* From Hinde’s description and 
remarks on the only known species, A. oblonga Salter, (Catal. Foss. Sponges, Brit. 
Mus., p. 154, 1853) we learn that the lower half of the sponge is composed of “closely 
approximated, straight, elongated, conical spicules, about 3 mm. in length, and 
from .75 to 1 mm. in width, arranged so that their rounded summits form the outer 
surface of the sponge, whilst their obtuse points reach to its central axis.” The 
upper part of the sponge is said to consist of small cruciform and five- (possibly six-) 
rayed spicules, and of very minute filiform mon-axial spicules, while “in one speci- 
men there are indications of an exterior surface-layer of filiform spicules regularly 
arranged in the direction of the length of the sponge.’ The spicules seem in no 
case to have been organically attached to one another, nor are canals present, but a 
narrow tubular cloacal cavity was detected in the lower part of a few specimens. 
Salter regarded the spicules as triradiate, and Hinde admits that when not 
detached from the mass “only casts of three rays are exposed.” The surface of the 
upper part, as figured by Hinde (op. cit.) resembles part of the surface of casts of 
species of Jschadites so closely that it is a matter of surprise that so keen an observer 
as Dr. Hinde failed to make a note of it in his memorable work on the Receptaculitida. 
The supposed surface-layer, with its longitudinally arranged filiform spicules, 
causes me to think it possible that the horizontal rays in A. oblonga may really be, 
as in Anomalospongia, three in number, with the longitudinal ray the strongest. At 
any rate it would be well to re-examine Amphispongia oblonga in the new light fur- 
nished by Anomalospongia reticulata. The club-shaped spicules of the lower part of 
the sponge are too much like the vertical ray of the spicules of Anomalospongia to be 
without significance entirely. My impression is that the lower spicules of Amphi- 
spongia ave not really mon-axial, but will be found to have head rays similar to if not 
precisely like those of Anomalospongia. Further, is it not possible that the same kind 
of entering rays (only smaller, perhaps,) occur in the upper part of the sponge as 
well, being covered there by the matrix which may intervene at a constriction just 
beneath the horizontal rays, and thus present to view the casts of the latter only ? 
Again, it is possible that the so-called “upper part” of A. oblonga may really owe its 
comparative smoothness to the development of a dermal layer consisting of small 
cruciform and filiform spicules. But this is only speculation. What is wanted are 
facts showing the true condition of things in Amphispongia, and I hope some of our 
British paleontologists will favor us with a full account of them. In the meantime 
we can use only the close approximation and the shape and size of the spicules of 
the lower part in showing the relationship which I am satisfied will sooner or later 
be proven to exist between the two genera. 
*The specimens are moulds in shaly rock merely, the sponge spicules themselves having been dissolved completely 
away. 
