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 (d). 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) bears a series of simple filiform tentilla (ts). 



Fig. 5. A mature corm of Cydalia monogastrica, representing a single cormidium. p, Pneumatophore;^/', 

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

 stomach ; s?-, proboscis ; ss, mouth ; t, tentacle ; gd, monostylic gonodendron. 



Figs. 6-8. E'pibulia ritteriana, n. sp. (p. 335). 



Fig. 6. A mature conn 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 ; pit, 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. 



