564 



MOLLUSCA 



PHYLÜM VI 



Borsonia Bellardi (Fig. 1049). Outer margiii witli a sliallow notch ; canal long 

 aud straight ; columella with one or two folds ; operculum iinknown. Eocene to 

 Recent. 



Mangilia Risso (Fig. 1050). Shell small, fusiform, imperforate and typically, 

 with longitudinal costae or swellings. Aperture commonly narrow, with a short, 



Fig. 1049. 



Borsonia delucii 

 Nyst. Lower Oligo- 

 cene ; Lattdorff, near 

 Bern bürg. 



Fig. 1050. 



Mangilia angusta 

 Jan. Plioeene ; 

 Occiano, near Pisa. 



Fig. 1051. 



A, Clathurella strom- 

 hilla Duj. Miocene ; 

 Kienberg, near Vienna. 

 B, Bellardiella reticu- 

 lata (Brocchi). Plio- 

 eene ; Sassuola, near 

 Modena. 



Fig. 1052. 



Daphnella (RapJd- 

 toma) vnlpecula 

 Brocchi. Plioeene ; 

 Sassuola, near 

 Modena. 



trimcated canal ; no operculum ; sinus near the suture. Outer margin usually acute, 

 not dentate posteriorly with shallow notch. Tertiary and Recent. 



Allied genera are the following : Clathurella Carp. (Fig. 1051, Ä) ; Bellardiella 



Fischer (Fig. 1051, B) ; Atoma Bellardi; Glypho- 

 stoma Gabb ; Daphnella Hinds, with subgenus Raphi- 

 toma Bellardi (Fig. 1052) ; Eucythara Fischer, etc. 



Family 4. Oonidae Adams. 



Shell convolute, turhinate or suhcylindrical, 

 generally smooth. Spire short, conical or ßattened. 

 Aperture long, narrow, anteriorly notched. Outer lip 

 sharp, sometimes with an anal sinus helow the suture. 

 Golumella smooth. Operculum horny. Cretaceous to 

 Recent. 



This family is now enjoying its acme of 

 development, having entered upon its ascendency 

 during the Tertiary. The typical genus, Conus 

 Linn. (Fig. 1053), is divided by malacologists into 

 Ä, Conus ponderosus Brocchi. Miocene; numerous subgenera, connected with one another 

 Lapugy, Transyivania. B, c. parisiensis by intermediate fomis. It is initiated in the 



Desh. Calcaire Grossier; Grignon, near r^ , 



Paris. Cretaceous. 



Gonorhis Swains. Characterised by a high 

 spire, and a curved, outer lip, which is deeply notched posteriorly. Eocene and 

 Oligocene. 



Fig. 1053. 



Subclass 2. EUTHYNEURA Spengel. 



Gastropods in which the visceral nerve commissures are not crossed, hut form a simple 

 loop ; the sexes are united (hermaphroditic) ; and the heart is often in front of the gill. 

 Shell Spiral or saucer-shaped, frequently vestigial or absent ; operculum generally wanting. 

 Radula generally multiserial. 



