432 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loi 



quickly aborally; distally it runs over gradually into the muscle 

 meshes of the capitulum, which are arranged in a single row (fig. 

 81, a) . The lobes of the capitulum are very numerous, the tentacles 

 thin and delicate and extraordinarily numerous, certainly more 

 numerous than those of Metridium. They appear as a rim on the 

 end of the lobes and their arrangement is impossible to determine, 

 and it is even difficult to distinguish the directive tentacles from 

 the others. The inside of the lobes and the outside of the fold are 

 provided with well-developed ectodermal radial muscles (fig. 81, 

 a). The inner part of the oral disc, which is devoid of radial 

 muscles, is very wrinkled and broad, but narrow at the directives 

 owing to the occurrence of very large gonidial tubercles. The very 

 broad siphonoglyphs, symmetrically set, are prolonged almost to 

 the base of the body. The retractors are diffuse, strongest in the in- 

 nermost parts of the mesenteries and there forming palisadelike 

 folds. The mesogloea of the filaments, especially that of the middle 

 tract, is very thick in the region of the ciliated tract of the perfect 

 mesenteries. The ova are small, the acontia thin but numerous. 

 Plate 14, figure 4, shows a part of the oral disc with the tentacles 

 and the fold, which is radially furrowed (at x) on its inside; figure 

 81, a, a longitudinal section of the capitulum and the fold; figure 

 81, b, part of sphincter in the scapus. 



Family SAGARTIIDAE 



ANTHOTHOE PANAMENSIS (Verrill) ? 



Figure 81, c 

 Sagartia pana7nensis Verrill, 1869, p. 484. 



Pedal disc wide, attached to I'urritella-like snails. Column trans- 

 lucent showing the insertions of the mesenteries. The body forms 

 a cone in contraction. Sphincter (fig. 81, c) alveolar, strong. Ten- 

 tacles delicate, of moderate length, fewer than the mesenteries at 

 the base. Two siphonoglyphs and two pairs of directives. Mesen- 

 teries of the first and second cycles perfect. Retractors diffuse, 

 rather strong with high folds ; the parietobasilar muscles well de- 

 veloped, forming a shelf on the weaker mesenteries. The weaker 

 mesenteries of a sectioned individual are provided with ovaria, but 

 the stronger are seemingly sterile and therefore the species may 

 be an Anthothoe. The nematocysts of the column are partly 17-19.7 

 by 2.8-3.5 /x (basitrichs), partly 12.7-16.2 by 2.8-3.5 /. (probably 

 microbasic 2^-mastigophors) , both often somewhat curved; those 

 of the tentacles partly 15.1-21.1 by 2.5-2.8 fx. (basitrichs), partly 

 18.3-21.8 by 4.2 /a (often curved, microbasic p-mastigophors or 

 amastigophors) ; those of the actinopharynx partly 19-25.4 by 



