78 Dr. G. J. Hinde on the Genus Hindia. 



scale as the longitudinal section. In the silicified examples 

 from Tennessee the casts of the spicules on the outer surface 

 of the sponge are shown as A-shaped depressions, with minute 

 circular holes at each of the angles, indicating the centres and 

 rays respectively. 



Considerable differences of opinion have been expressed as 

 to the systematic position of Hindia. Dr. Rauff regards it as 

 belonging to the Tetracladine family of lithistids ; Zittel 

 places it with the Megamorina ; whilst I have ranged it 

 under the Anomocladina. Dr. RaufF maintains that the 

 number of the rays (when four are developed) and the angles 

 at which they are given off from the centres correspond with 

 those of Tetracladine spicules. On the other hand, the general 

 characters of the elementary spicules and their mode of union 

 with each other appear to me to indicate a closer relationship 

 to typical Anomocladine sponges. The spicule fundamen- 

 tally consists of a central node giving off simple rays with 

 expanded terminations, which clasp the centres and convex 

 surfaces of other spicules. In these features Hindia resembles 

 such recognized Anomocladine genera as the Silurian Astylo- 

 spongia, F. lioemer, the Jurassic Cylindrophyma, Zitt., and the 

 recent Vetulina, 0. Sdt. In typical Tetracladine sponges, on 

 the other hand, the four rays of the spicules radiate from a non- 

 inflated centre ; they usually branch near their extremities, 

 and they join together by the interlocking of the branched ends 

 with each other, thus materially differing from Hindia, It is 

 true that the number of the rays is the same in Hindia as in 

 Tetracladine sponges ; but then one ray is only incipiently de- 

 veloped, and the resemblance in this respect appears to me to be 

 more than counterbalanced by the material differences in others. 



In the general regular construction of its skeleton, Hindia 

 finds a close parallel in Astyhspongia and Cylindrophyma ; 

 and in the particular feature of the disposition of the spicules, 

 so that they form a series of arches, with the convexity 

 towards the exterior, and the nodal summit of each arch 

 supporting the bases of the arches next above, there is a close 

 resemblance to the existing genus Veiulina, in wliich 8ollas * 

 has described a precisely similar arrangement. In no other 

 family of lithistids is there, to my knowledge, the same regular 

 construction of the skeleton as in Hindia and the other Ano- 

 mocladine genera above mentioned, and I think therefore its 

 true position is in this family in near proximity to the con- 

 temporary genus Astyhspongia. 



Some recent discoveries show that Hindia had a very wide 



* " On Vetulina stalactites, 0. Sdt., and the Skeleton of the Anomo- 

 cladina/' Proc. Roy. Irish Acad. 2nd ser. vol. iv. no. 4, p. 491. 



