2 22 SECTION C. INVERTEBRATA. 



Panama, at the depth of nearly 300 fathoms. The most striking 

 features of the animal are a strongly-expressed bilateral symmetry, 

 and the possession of an incomplete circle of gill-like organs arising 

 from the disk near the base of the oral tube. The disk is very 

 oblique to the chief axis of the animal and its edges are apparently 

 incurved in life so as to give the anterior end of the actinian a vase- 

 like or scoop-shaped appearance. The circle of marginal tentacles 

 suffers an interruption corresponding in position to that of the circle 

 of gills. The smallest and youngest tentacles are nearest this 

 hiatus. Radiating canals run across the disk from the base of the 

 oral tube to the tentacles, with the cavities of which they communi- 

 cate. The lower end of the swollen bulb-like column is provided 

 with numerous small filamentous projections, and the case secreted 

 by the basal end of the column also has long hollow filaments, 

 which serve to anchor the small (three to four decimeters long) 

 animal in the mud. Drawings illustrating these facts were shown. 

 A more complete account will be found in Bull. Mus. Comp. Zool. 

 at Harvard Univ., Vol. 32, No. 8, entitled Preliminary Report on 

 Branchioceriantlms tirceolus. 



5. On the range in time and space of Fnsus {Neptnned) 

 antiqniis AND ITS ALLIES (with Plate 3). 



By Mr F. W. Harmer. 



The question of the specific identity or otherwise of the different 

 dextral and sinistral forms of mollusca, of which Fnsns antiqims 

 (now generally referred to the genus Neptnned) may be taken as 

 the type, is one upon which considerable difference of opinion has 

 existed. It is possible that the study of their geographical distribu- 

 tion, at the present day, and during the Pliocene epoch, may throw 

 some light on the subject. 



In the second edition of Lamarck's Histoire Natnrelle des 

 Animanx sans Vertebres (Vol. IX. 1843), the names of five allied 

 forms are given, which are there regarded as specifically distinct. 

 Of these three are dextral, viz. : 



Fnsns antiqims^ Linn. 

 „ carinatns. Pennant. 

 „ despeet?ts, Linn. 



and two sinistral, viz. : 



Fnsns contrarins, Linn. 

 „ sinistrorsiis , Desh. 



These two groups now occupy distinct areas, which do not, ex- 

 cept perhaps with rare exceptions, overlap. Specimens of the latter 

 have been recorded, although with some doubt, from the Mediter- 

 ranean^, and they are found on the coast of Portugal, but I am not 



1 Meli, Boll, della Soc. geol. ital., vol. xiii. (1894), fasc. 2. 



