HINDIA. 115 
Genus.—Hinpia, Duncan. 
1879. Ann. and Mag. Nat. Hist., ser. 5, vol. iv, p. 84. 
Syn.—Calamopora, F’. Roemer (non Goldfuss), Steinmann ; Spheerolites, Hinde. 
Sponges spherical or sub-spherical in form, free, without stem or any surface 
of attachment. The body of the Sponge is traversed throughout by straight, 
simple, subcylindrical or prismatic, sub-equal canals, radiating, in close proximity 
to each other, from a central space, and opening freely at the surface. The 
skeleton consists of spicules generally with four rays (though occasionally only 
three are developed) which extend from a compressed central node. Three of the 
rays are sub-equal, whilst the fourth is truncated. The rays terminate in flattened, 
circular, irregularly digitate expansions, which firmly clasp the nodes and convex 
surfaces of the rays of adjoiming spicules in such a manner as to form an extremely 
regular meshwork, with transversely elliptical interspaces. 
Specimens of this genus from West Tennessee were originally described as 
corals by F. Roemer’ under the name of Calamopora fibrosa. They occur as 
silicified casts, in which the original structure has been entirely removed ; and in 
this condition they resemble very closely small silicified corals. Without being 
aware of F. Roemer’s reference of the forms to corals, I made a similar mistake 
respecting forms which I had collected from New Brunswick, erroneously regard- 
ing them as perforate corals, which I named Spherolites.2. My specimens were 
afterwards submitted to Prof. M. Duncan,’ who recognised the spicular nature of 
this skeleton, and constituted them into a new genus of Sponges, which he named 
Hindia. The original silica in these specimens had been replaced by calcite, but 
Prof. Duncan, maintaining that the skeletons were originally of calcite, principally 
on the ground of the supposed presence in them of a parasitic Alga, regards the 
forms as Calcisponges, representing a former mimetic and calcareous group of 
Spongida. Their general structure corresponds so closely with that of Lithistid 
Sponges that I felt justified in placing the genus in the Anomocladina family of 
this group ;* Zittel,” however, regarded the genus as more properly coming within 
the Megamorina family. A later writer,’ Dr. Steinmann, has asserted that the 
genus exhibits none of the characters of Lithistid Sponges, and that it really 
1 «Die silur. Fauna d. westl. Tenn.,’ p. 20. 
2 «Abstract Proceedings Geol. Soc.,’ 1875, No. 305. 
3 «Ann. and Mag. Nat. Hist.,’ ser. 5, vol. iv, p. 84, 1879. 
4 ¢ Cat. Brit. Foss. Spong.,’ p. 57, 1883. 
> * Neues Jahrb.,’ 1884, Bd. ii, p. 79. 
5 Thid., 1886, Bd. i, Heft i, p. 91. 
