new Mollusca from Aden. 203 



Hah. Aden {Capt. E. R. Shopland and Major J. W. Yer- 



hury) . 



A fine and critical species. It is to Captain Shopland and 

 Mr. Edgar Smith I am indebted for first pointing out the 

 differences between it and T. madagascariensis, Grael. 

 Though, looking cursorily, they might at first be considered 

 identical, they differ in several important particulars, e. g. : — 



T. madagascariensis. T, manumissa. 



i. Substance thick. Of thinner texture than its con- 



gener. 

 ii. Posteriorly rostrate. Posteriorly simply oblong, 



iii. Plainly spirally striate. Plainly spirally striate, and like- 



wise longitudinally microscopically 

 striato-decussate. 

 iv. Within, entirely red. Within, red centrally, but white- 



margined. 

 V. Pallial line at a wider and Pallial line at a higher and more 

 more extended angle. acute angle. 



There likewise exists a slight similarity to T. planata, L., 

 from the Mediterranean, and to T. strigosa, Gmel. 



The fine example collected by Major Yerbury is now in 

 the British Museum, and was catalogued by Mr. E. A. Smith 

 as madagascariensis (Proc. Zool. Soc. 1891, p. 426). 



TelUna {Anqidus) yemenensis, sp. n. 

 (Pi. XII. fig. 11.) 



T. testa insequilaterali, convexa, ovato-oblonga, antice rotundata, 

 postice angustata, albo-rosea ; umbonibus approximatis, depressia, 

 parvis ; valvis niteutibus, iridcscentibus, arete et delicatissime 

 concentrico-striatis ; margiue dorsali autice leniter rotundato- 

 declivi, postice recti uscule-doscendeiito, margiue cum ventrali 

 augulum fere acuminatum formante ; intus superfieie albescente, 

 vel albo-rosea, vel omnino rosea, pra3cipue versus umboues, sinu 

 palliali extenso profundo. 



Long. (sp. maj.) 13, alt. 10, diam. 3-50 mm. 



Much resembling; T. corbuloides, Hanley, with which I at 

 first deemed it identical. A closer inspection, however, 

 decided me that it was altogether distinct. The surface is, 

 to begin with, iridescent, altogether more shining than corbu- 

 loides, the umbones in this last being more prominent and 

 larger and the anterior slope of the dorsal margin slightly 

 more rounded. The angle formed at the junction of the 

 oblique dorsal posterior slope with the ventral margin is more 

 acuminate and the ventral margin itself sinuoso-convex. 

 Several specimens, which differ mainly in colour, some being 



16* 



