1901.] MOLLUSKS FROM THE PERSIAN GULF. 379 



r/radatis, apud suturas canaliculato-impressis, spiraliter tri- 

 car inatis, carinis prcecipue apud medium binis, conspicnis, acutis, 

 2>rominulis, gemmulatis, ultimo anfractu quadricarinato, super- 

 Jicie interstitiali inter carinas principalis regulariter quadrata, 

 infra suturas excavata ; apertura ovato-quadratula, labro tenui, 

 angulari ; columella fere recta. 

 Long. 11, lat. 4 mm. 



Hob. Gulf of Oman : lat, 24° 55' N., long. 57° 59' E. 37 

 fathoms, sand and mud bottom. 



In form turritelloid, gradate, becoming rapidly attenuate, white, 

 delicate, 8- or 9-wborled, two of these being apical, globular, 

 smooth, glassy, the rest thrice (the lowest whorl four times) keeled, 

 the two lowermost carinse being acute, prominent, conspicuous ; 

 the interstitial ground between the carina? is regularly divided into 

 quadrate spaces, a small gemma or nodule being present on the 

 keels at the points of transition. The mouth is squarely oval ; 

 outer lip thiu, angled, columella almost straight. A very remark- 

 able species ; conspicuous for its graceful, attenuate form. 



Mathilda zmitampis \ sp. n. (Plate XXII. fig. 19.) 



M. testa turrita, gracili, fusiformi, delicata, cdba ; anfractibus 9, 

 quorum apicales duo conspicue heterostropM, mamillati, vitrei, 

 perlceves, ccttcris apud suturas impressis, deinde supra, ju.vta 

 suturas, spiraliter acute bicarinatis et biliratis, undique longi- 

 tudinaliter arete costaiis, costis acutis, angustis, tenuibus, ad 

 juncturas lirarum gemmulatis, interstitiis alveatis, quadratidis ; 

 aperturafere rotunda, alba; labro tenui, extus crevoidato; columella 

 paullum incrassata, cdba, nitida ; ultimo anfractu ad basim 

 spiraliter tomato, fortitt-r striatulo. 

 Long. 10, lat. 3*50 mm. 



Hub. Gulf of Oman : lat. 24° 5' N., long. 37° 35' E. 208 

 fathoms, sand. 



We are not satisfied with the present location of Mathilda 

 Semper (1865) amongst the Turritellida?, Dr. P. Fischer (Man. de 

 Conch, p. 695) styles the genus as possessing the shell of Turritella, 

 with the embryonic heterostrophe-whorls of the Pyramklellidcp ; but 

 in that case we should consider that its alliance would be with the 

 latter family. Certain of the Odostomire possess the same fenestrate 

 and alveolate sculpture, Twbonilla fenestrata Forbes, for example. 

 The species before us is most elaborately chased and ornamented 

 with four spiral carina?, two being little more than striations or 

 lira' : tin.- two lower bolder, acute, and giving an angled contour 

 to the whorls. The longitudinal thin costac, crossing these carina 

 and lira? at right angles, form quadrate interstitial divisions. The 

 whorls are nine, two of which are apical, heterostrophe, and 

 crystalline. The mouth is roundly oval, outer lip rather thin ; 

 columella white, shining. 



1 Zmttuinjjts, a pnoiOUl liOIU incut ioiifd by Pliny. 



