564 



MOLLUSCA 



PHYLUIM VI 



Borsonia Bellardi (Fig. 1049). Outer margin with a shallow notch i canal long 

 and straight ; columella with one or two folds ; operculum unknown. Eocene to 

 Recent. 



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

 with longitiidinal costae or swellings. Aperture commonly narrow, witli a short. 



B 



Fig. 1049. • 



Borsonia delvcii 

 Nyst. Lower Oligo- 

 cene ; Lattdoiff, near 

 Bernburg. 



Fig. 1050. 



Mangilia anguMa 

 Jan. Pliocene ; 

 Occiano, near Pisa. 



Pio. 1051. 



A, Clathurella strom 

 billa Duj. Miocene 

 Kienberg, near Vienna, 

 B, BeUardkila reticu 

 lata (Brocchi). Plio 

 cene ; Sassuola, near 

 Modena. 



Fig. 1052. 



Daphnclla {Raphi- 

 toma) vulpccnla 

 Brocclii. Pliocene ; 

 Sassuola, near 

 Modena. 



truncated 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: Glathurella Carp. (Fig. 1051, A); Bellardiella 



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

 stoma Gabb; Daphnella Hinds, with subgenus Baphi- 

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



Family 4. Oonidae Adams. 



Shell convolute, turbinate or subcylindrical, 

 generally smooth. Spire short, conical or flattened. 

 Aperture long, narrow, anteriorly notched. Outer lip 

 sharp, sometimes with an anal sinus belov: the suture. 

 Columella 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 



.1, ro««s ponto-o7«,rBrocchi. Miocene; numerous subgenera, connected with one another 

 Lapugy, Transylvania. B, c. iMviumnis by intermediate fomis. It is initiated in the 

 Part. Calcaire Grossier; Grignon, near c,.ej.ace0US. 



Gonorbis Swains. Characterised by a liigh 

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

 Oligocene. 



FiQ. 1053. 



Subclass 2. EUTHYNEURA Spengel. 



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

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

 Shell spiral or saucer-shaped, fi'equently vestigial or absent ; operculum generally wanting. 

 Radula generally multiserial. 



