488 JOHNSON. [Vol. VIII. 



3. Pharyngeal Funnel. 



That portion of the frontal field that sinks spirally into the 

 animal was regarded by Stein and later writers as the 

 oesophagus, and its external aperture as the mouth. But 

 Schubcrg ('90, p. 202) has shown conclusively that the whole 

 funnel is an in-turned portion of the frontal field, and that 

 the real mouth lies at its innermost extremity (Figs. 35, 62, 0). 

 Schuberg has very accurately figured (Taf. XIV, Figs. 2, 3) 

 the appearance of the pharyngeal funnel of 5. cceruleus in the 

 contracted state. With the extension of the animal, the 

 funnel undergoes great enlargement, and the outer turn, or 

 buccal pouch (Figs. I, 33, 62, b.p.) (" Peristomtasche" of Stein) 



a.z.' 



fig- I- — Diagram of frontal field and pharynx uf 6". cceruleus, expanded. 

 a. z., adoral zone ; b.f., buccal fold ; b.p., buccal pouch ; //?. pharynx ; vel., velum. 



sometimes attains nearly one-half the area of the whole frontal 

 field. It serves as a very capacious "hopper" for whatever 

 grist is brought by the " alimentary vortex." If one looks 

 directly down upon the frontal field, the buccal pouch is seen 

 to have an outline varying from almost circular in state of 

 utmost expansion, to reniform and crescentic according to the 

 amount of distension (Fig. I, b.p.). It also varies much in 

 different individuals. The concave side of the crescent is 

 always dorsal; the convex outline is formed by the " hypostom " 

 of Stein. This hypostom is the thin raised edge of the 

 ventral body-wall, crowned with the adoral zone as it passes 

 towards the right to enter the funnel. Inasmuch as the name 



