SPONGES. 247 



0.5 mm, to nearly 2, mm., and are arranged in an obscurely 

 radiate manner. The branches are composed of small irregularly 

 branched spicules (fibre?) which are compactly interwoven in 

 the central region of the branches, but more loosely near the 

 surface, where their form is approximately determinable. The 

 branchlets of the spicules are slender and pointed, and project 

 in all directions, so that the branches, when magnified, have a 

 very spiny appearance. Extremely minute a/cerate spicules, 

 scarcely 0.5 m.m. long, occur between the branched spicules, and 

 in the matrix filling the space between the sponge branches. 



So far as they can be made out the spicules of this species, 

 agree, in a general way, with those belonging to the Lithistid 

 family Rhizomorina. On the other hand the magnified branches 

 are not unlike the spiny fibres of some of the Calcispongiae 

 (e. g. Peronella). and I do not consider it at all improbable, 

 that better preserved examples will show that, instead of irregu- 

 lar four-rayed spicules with bifurcated rays, the spicules are 

 really three-rayed. Their association with numerous minute 

 acerate spicules, is more indicative of the Calcispongiae than the 

 Lithistida. Another circumstance suggesting an originally cal- 

 careous skeleton, was observed in freeing fragments of the sponge 

 from the rock by treating with acid. One specimen proved to 

 be siliceous, a fragment of another was so only in part, while 

 the third (the specimen represented by fig. 2) proved, unfortu- 

 nately, to be entirely calcareous, as it was nearly destroyed 

 before its character was noticed. The residue of a part of the 

 last specimen contained, beside numerous spicules of Hystrio- 

 spongia, also several small partially silicified fragments of 

 bryozoa. 



None of the Calcareous or Lithistid genera of sponges with 

 which I am acquainted, sufficiently resemble Batospongia to 

 necessitate detailed comparisons. 



Position and locality: The specimens are contained in a slab 

 of bituminous limestone obtained from a layer near the base of 

 the Coal measures, at Seville, 111., where they are associated with 

 Hystriospongia carbonaria, Hyalostelia delicatula, and numer- 

 ous brvozoa. 



