26 



Diagnosis. Shell solid, pale amber coloured or whitish, acuminate in young, strono-ly 

 truncated in adults. Sculptured with nine to twelve strong equidistant ribs which are generally 

 bisected by a longitudinal groove. Interstices twice as wide as the ribs sculptured with 3 — 4 

 slightly raised riblets and decussated (especially near the apex) by extremely minute transverse 

 lines. Apex generally slightly notched on the convex side and internally lined with a small rim 

 or a short supplemental tube. Anterior aperture not oblique. 



a. Length of young attenuated specimen 18, diam. of aperture 3,2, diam. of apex 0,6 mill. 



b. Length of older specimen 35, diam. of aperture 4 of apex 2,3 mill. 



c. Length 42, diam. of aperture 5 of apex 1,8 mill. 



d. Length 50, diam. of aperture 6,5 of apex 22 mill. 



Distribution. Gulf of Suez. 



Remarks. This species strongly resembles D. B e lek er i Sow&rhy. Some of the younger 

 specimens are faintly maculated on the ribs, and the resemblance is then greater still. It differs 

 however in having the ribs longitudinally bisected and by the close transverse striation near 

 the apex. 



The description and the figures are made after specimens in the Mac-Andrew collection 

 of Cambridge. Mr. Cooke distinguLshed them into three species, but after having carefully 

 examined all the specimens referring to his .species I have come to the conclusion that they 

 all belong to the same specific form. Probably he was deceived by the great dissimilarity of 

 form due to difference in age. Like D. intercalahuu^ novemcostatum, trtincatum and many other 

 De7italiidae this species is less curved in old age, while the apex becomes more and more 

 truncated, until in some specimens the shell is almost equally wide from apex to anterior aperture. 



The specimens, afterwards named aratorum by Mr Cooke had been labelled D. Reevii 

 Desh. MSS. by Mr Mac-Andrew. I do not know whether the latter had compared these with 

 authentic specimens of Reevii, or that he drew his conclusions from the insufficiënt note of 

 FiscHER on that species. I agree however with Mr Pilsbrv that Fischer's provisional note 

 gives too little Information to make an Identification possible and therefore do not adopt 

 Deshayes's MSS. name. 



The same is the case with D. laitgieri Jousseaume which perhaps is identical with or 

 at least nearly related to this species. 



Here follow the descriptions. 



D. lineolatuin Cooke. PI. V, figs 25, 26, 27. 



.Shell solid, pale amber coloured, acuminate, curved toward the apex, 

 fluted with 9 angulated, very high equidistant ribs; interstices and some of the 

 ribs themselves longitudinally lineated, and decussated by very minute transverse 

 striae. Apex entire. Length 1,75, breadth at base 0,25 inch. (Cooke). 



Gulf of Suez (Mac-Andrew). 



Fig. 16. Anterioi- 



apevtuve of "/). In fresh specimens the interstitial lines are very marked ; they are parallel 



tnco auirn oo e . ^^ ^^ x)}c)^, which are themselves generally bisected by a similar line. (Cooke). 



