[ 139 ] 



No. XVII.— REPORT ON THE BRACHIOPODA OBTAINED FROM THE 

 INDIAN OCEAN BY THE SEALARK EXPEDITION, 1905. 



By William Healet Dall, A.M., Sc.D., Curator Div. Moll. U.S. Nat. Mm. 



{Communicated by Prof. J. Stanley Gardiner, M.A., F.R.S., F.L.S.) 



(Plate 26.) 



Read 2nd December, 1909. 



The Brachiopods transmitted to me for examination by Mr. J. Stanley Gardiner were all 

 obtained from one haul of the dredge on the descending soutliern slope of the sea-bottom 

 south of the Saya de Malha Banks. The haul, which was made over bottom beginning 

 at 153 and ending at 123 fathoms, was numbered " C 1." 



The collection comprises one badly crushed Liothyrina, of which only the posterior 

 portions remain, two specimens of Avhat appears to be a new species of Kraussina, and 

 seven specimens of a new Hemithyris. 



Brachiopods are usually very free from adherent growths when living, but these 

 specimens were badly encrusted with patches of Serpulge, Polyzoa, and sessile 

 Poraminifera. 



1. Liothyrina sp. indet. (Plate 26. figs. 1, 2.) 



This species, as far as could be judged from the imperfect remains, was of an inflated 

 form recalling that of L. bartletti of the Antilles. The surface was smooth except for 

 lines of growth, was of a pure white colour, and moderately poUshed. The lower valve 

 (represented by a portion bearing part of the broken apophyses) was destitute of any 

 medial septum or props to the hinge processes. By assembling camera-lucida sketches 

 of the fragments I have made a diagram (fig. 1) of the apophyses which may assist in 

 recognizing the species when well-preserved specimens are obtained. The beak of the 

 lower valve is provided with a small cardinal process composed of a projecting callous 

 deposit, like half a rosette, to which the posterior ends of the muscular fibres which 

 separate the valves (" divaricators " of Hancock) are attached. The general form of the 

 loop resembles that of L. sphenoidea, Philippi. The soft parts were badly mutilated, but 

 it was possible to discern a small mesial coil of the brachia. 



A feature rather unusual in this group was that the ovaries, which were of a creamy- 

 white colour, seemed to be entirely enclosed in a space of which the boundaries followed 

 the outline of the muscular attachments, and at but a short distance outward from the 

 latter ; while in most of the known species, in fact in almost if not quite all of them, the 

 ovaries and the genital sinuses are produced in narrow lines or in a branched manner 

 nearly to the anterior margins of the valves. 



Blochmann has shown that the spicula of the mantle in Brachiopods are specifically 



