196 SYSTEMATIC ARRANGEMENT 



§§§§ Teeth in very numerous close longitudinal series, forming 

 oblique cross series (fig. 1 11). 



Fam. IV. BULLID^. 



Teeth : central one, distinct ; lateral numerous, uniform, in an 

 angular series. Tentacular frontal disk expanded, nicked behind. 

 Shell distinct, exposed. 



* Mantle with a long process emitted through a slit in the suture, 

 of the shell. Head disk narrow. Eyes none. Spire convex. 



1. Akera. 



Head disk elongate, narrow, simple. Eyes none. Mantle en- 

 closed, fringed on the edge. Foot very large ; sides dilated, rounded, 

 folded back in repose. Shell subcylindrical, convolute, thin, elastic ; 

 spire short ; suture channeled, notched on the edge. 



1. A. bullata, t. 60*. f. 6, 7. Forbes fy Hanley, B.M. t.V.V. f. 6. 



2. A. 1 n. s., t. 178, f. 2. Borneo. 



Central tooth of Akera bullata minute, erect, base wider, produced 

 on each side ; head swollen, impressed above, cutting edge deflected, 

 one-pointed, on each side crested and toothed ; lateral teeth about 

 twenty-one, with a long hook, the middle ones longest, the first 



Fig. 111.— Teeth of Akera bullata. 



shortly winged on the inside, serrulated, the following gradually more 

 and more slender (fig. 111). — Lovdn. 



** Mantle simple behind. Head disk broad. Eyes distinct. 

 Spire of shell minute, sunk ; suture simple. 



2. Bulla. 



Head disk broad, sometimes nicked and expanded behind. Eyes 



subcentral. Mantle enclosed, with a thick posterior lobe. Foot 



oblong, short; front part of sides bent up. Shell ovate, solid, 

 coloured, involute ; spire very small, sunk or hidden. 



1. B. Cranchii, Forbes <$• Hanley, B.M. t. V.V. f. 2. 



2. B. ampulla, t. 178. f. 3. 



3. B. ovoidea, t. 59. f. 4. 



4. B. glauca, t. 59. f. 3. 



5. B. striata, t. 60. f. 2, t. 175. f. 4. 



