1873.J DR. J. S. BOWERBANK ON THE SPONGIADjE. 319 



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Height at shoulder 1 \ j 



Length of fore leg \ 4.5 



Length from knee to fetlock (metacarpal joint) 6*5 



Length from fetlock to end of toe 3-5 



Length of hind leg 1 \ 1 



Length from hock to fetlock (metatarsal joint) 9-25 



Length from fetlock to toe 3*25 



Length of horn from base to point, measured in a straight line 7*25 



This Gazelle is distinguished from G. bennetti, 1st, by colour. 

 The face in the Indian Gazelle is nearly uniform rufescent fawn- 

 colour, the parts which are black or blackish in G.fuseifrons being 

 only a little darker than the rest in G. bennetti ; the back also in 

 the latter is more rufescent and less yellow, and the hairs are less 

 dense. 2nd, by the greater length and more strongly marked 

 annulation of the horns in the female, and by their well-marked 

 curvation forwards towards the extremities. The horns in the 

 female of G. bennetti are smaller than those of the male to a much 

 more marked extent than in G. dorcas ; the new species in this respect 

 agrees probably with the African, and not with the Indian type. 



From G. dorcas, G. arabica, and all allied forms the present 

 species is also distinguished by the curvature of the horns and the 

 coloration, especially of the face, none having such strong dark 

 patches on the forehead and nose. 



Of the habitat of this Gazelle nothing is known beyond what has 

 been mentioned above. It has probably a wide extension through- 

 out the deserts of Eastern Persia ; and perhaps, as suggested above 

 in referring to the notes by Dr. Jerdon on Gazella christii, it may 

 extend into India. It probably, in Eastern Persia, inhabits the fla"t 

 desert at a comparatively low elevation, whilst G. subgutturosa 

 occurs along the bases of the hills and in the higher valleys. 



2. Contributions to a General History of the Spongiadce. 

 By J. S. Bowerbank, LL.D., F.R.S., &c.— Part V.* 



[Received January 3, 1873.] 

 (Plates XXVIII.-XXXI.) 

 Isodictya mirabxlis, Bowerbauk. (Plate XXVIII.) 

 Sponge virgultose. Surface smooth. Oscula simple, or very 

 slightly elevated ; margins thin, disposed laterally. Pores congre- 

 gated in small pocilla, covered by a radial arrangement of ten conical 

 sacculi, haying their apices central and their bases marginal ; pocilla 

 and sacculi abundantly spiculous ; porous areas arranged in shallow 

 canaliculi, disposed in short irregular lines, more or less in accord- 

 ance with the long axis of the sponge, bedded in a densely spiculous 

 * For Part IV. see antea, p. 3. 



