129 
(fig. 8); the piston (“lingual”) tooth armature consists of two parts— 
an anterior plate bearing two stout conical teeth and two posterior 
semi-crescentic flat plates, convex and smooth externally and straight 
and crenate on their inner opposed edges (figs. 15, 16, 17). The lateral 
aspect of the Velasia stage of Geotria australis is shown in fig. 10. It will 
be seen that apart from the great development of the suctorial funnel 
and the gular sac, its characters are similar to those of. the adult. 
SHALE 
Fig a0. 
Fig. 5 (x 1/,). Geotria australis in side view. 
Fig. 6 (x !/,). Head region in side view. 
Fig. 7 (x 2). Gill, external aperture. 
Fig. 8 (x 1). Ventral view of head region, showing dentition and gular pouch. 
Fig. 9 (x eirc. 10). Leaf-like sensory appendage from margin of buccal funnel. 
Fig. 10 (x !/,). Head region of Velasia stage. 
It may be mentioned that on the ventral side of the head and at the 
level of the eyes (i. e. in the position of the future gular sac) there 
are present two short rows of ueuromast sense organs, each row being 
situated about3 mm. from the mid-ventral line, and consisting of four or 
five organs. The teeth are also essentially identical with those of the adult. 
Anat. Anz. Bd, 45. Aufsätze, 9 
