HIPPOTHOIDtE. 25 



H. PATAGONICA, Busk, B. M. Cat., p. i, p. 30, pi. xvii, fig. 1. 



Alecto vesiculosa (?), Michelin, Icon. Zooph., p. 319, pi. Ixxvii, fig. 3. 



Habitat. — C. Crag, on Pecten, S. W. ; Hippurite limestone, St. Gregoire, near Rennes, 

 Michelin. [Recent), Coast of Patagonia, Falkland Islands, on fucus, Darwin ; Britain (?) ; 

 Tasmania. 



The Crag fossil corresponds in all respects with the Patagonian form. The circum- 

 stance that the latter would appear always to select a fucus for its base is probably in 

 this genus one of little importance. A species bearing considerable resemblance to the 

 present occurs in the Arctic sea, but is distinguishable by its mouth being larger and 

 without the notch at the lower margin. The cells, moreover, and their tubular pro- 

 longation, are less distinctly annulated. 



2. H. ABSTERSA, S. W. PI. XXII, fig. 6. 



Cellulis ovatis, elongatis, vel subpyriformibus, infra subattenuatis, sen potius pro- 

 ductis ; superficie glabro, compressis ; orificio suborbiculari subtus inciso ; ramis ascenden- 

 tibus, confer tis. 



Cells ovate, elongate, or subpyriform, very slightly attenuated or produced below, 

 smooth, compressed, or slightly raised in front ; orifice suborbicular, with a notch below ; 

 branches ascending crowded. 



L. ABSTERSA, <S. W., Ann. Nat. Hist., xiii, p. 19. 



Ckiserpia PYRiFoiiMis (?), Mich., Iconog. Zoopli., p. 332, pl. Ixxix, fig. 6. 



Habitat. — Coralline Crag, Walton, on inside of Pholas, 8. W. ; (?) Done (Maine et 

 Loire), Mich. ; Red Crag, Sutton, on Fectunculus glycimeris. 



3. H. DENTATA, 8. W. PI. I, fig. 7. 



Cellulis angustis, ovatis, lanceolatis, sen pyriformibus ; apertura ovali, margine spinoso ; 

 ramis angulo prope recto divergentibus. 



Cells slender, ovate, lanceolate, or pyriform ; aperture oval, margin spinous ; branches 

 divaricated nearly at a right angle. 



CaTENARIA DENTATA, (S. W., 1. C, p. 19. 



Habitat. — C. Crag, on shell, 8. W. 



The peculiar armature of the aperture in this species distinguishes it from H. 

 catenularia, with which in some conditions it might otherwise readily be confounded. 



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