1901.] MOLLUSKS FROM THE PERSIAN GULF. 379 



gradatis, apud suturas canaliculato-wipressis, spiraliter tri~ 

 carinatis, carinis prcecipue apud medium hints, conspicuis, acutis, 

 prominidis, gemmulatis, ultimo anfractu qiiadricarinato, super- 

 Jicie interstitiali inter carinas principales regulariter quadrata, . 

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

 angulari ; columella fere recta. 

 Long. 11, lat. 4 mm. 



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

 fathoms, sand and mud bottom. 



In form tur]'itelloid, gradate, becoming rapidly attenuate, white, 

 delicate, 8- or 9-whorled, 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 carincS 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 thin, augled, 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, alba ; anfractihus 9, 

 quonim apicales duo conspicue Jieterostrophi, mamillati, vitrei, 

 perlceves, cceteris apud suturas impressis, deinde supra, juxta 

 suturas, spiraliter acute hicarinatis et hiliratis, undique longi- 

 tudinaliter arete, costatis, costis acutis, angustis, tenuihus, ad 

 juncturas lirarum gemmidatis, interstitiis alveatis, quadratulis ; 

 apertura fere rotunda, alba; lahro tenui, extus crenulato; columella 

 paullum incrassata, alba, nitida ; idtimo anfractu ad hasim 

 spiraliter tomato, fortiter striatulo. 

 Long. 10, lat. 3*50 mm. 



Hah. 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 Turritellidce. Dr. P. Pischer (Man. de 

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

 with the embryonic heterostrophe- whorls of the Pyramidellidce ; but 

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

 latter family. Certain of the Odostomice possess the same fenestrate 

 and alveolate sculpture, Turhonilla fenestrata Porbes, for example. 

 The species before us is most elaborately chased and ornamented 

 with four spiral carinse, two being little more than striations or 

 lirse ; the two lower bolder, acute, and giving an angled contour 

 to the whorls. The longitudinal thin costte, crossing these carinse 

 and liras 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, 



^ Zmitampis, a precious stone mentioned by Pliny. 



