PLATE XXII. 



The figures of this Plate were drawn by me from life in Ceylon, in December 1881 and January 1882. 



Figs. 1-5. Cystalia monogastrica, n. sp. (p. 316). 



Fig. 1. Larva of an early stage, near to the gastrula. The spindle-shaped body is composed of a small- 

 celled ciliated exoderm (e) and a large-celled entoderm (<!). The incipient pneumatophore (p) is a 

 simple invagination of the apical pole. 



Fig. 2. Larva of a second stage. The medusiform body is divided by a transverse constriction into an apical 

 and a basal half ; the former includes the pneumatophore (containing an air-bubble), and is homo- 

 logous with the umbrella ; the latter includes the gastral cavity (sc), and is the primary siphon. 

 From the constriction arises a simple tentacle (t). The distal end of the siphon has a mouth- 

 opening (so), ps, Pneumatosac ; pf, pneumatocyst. 



Fig. 3. Larva of a third stage, differing from the preceding (fig. 2) in the formation of a bud (palpon), which 

 arises from the ventral side of the transverse constriction (/), opposite to the dorsal tentacle (t). 

 Characters as in figs. 1, 2. 



Fig. 4. Larva of a fourth stage. A corona of buds (palpons) arises from the base of the siphon below the 

 float. The tentacle (t) boars a series of simple filiform tentilla (As). 



Fig. 5. A mature corm of Gystalia monogastrica, representing a single cormidium. p, Pneumatophore;/)/, 

 pneumatocyst filled with air; pi, pneumatochone ; q, palpons; sb, basigaster ; sh, hepatic villi of the 

 stomach ; sr, proboscis ; ss, mouth ; t, tentacle ; gd, monostylic gonodendron. 



Figs. 6-8. Epibulia ritteriana, n. sp. (p. 335). 



Fig. 6. A mature corm of Epibulia ritteriana. p, Pneumatophore (compare the sections in figs. 7 and 8); 

 q, palpons ; qo, ocelli ; s, siphons ; sh, hepatic villi ; ss, mouth ; t, tentacles ; ts, tentilla ; gd, 

 gonodendra. 



Fig. 7. Vertical section through the axis of the pneumatophore. po, Apical ostium ; pu, pneumatocodon ; ps, 

 pneumatosaccus ; pp, pigment-cap (mitra ocellaris) ; pf, pneumatocyst ; py, pylorus infundibuli ; 

 pi, infundibulum (pneumatochone) ; pc, pericystic cavity ; pd, endocystic tapetum ; pv, hypocystic 

 villi ; at, cavity of the trunk. 



Fig. 8. Horizontal section through the pneumatophore. Characters as in fig. 7. 



