MEDUSA. 1G7 



Anthemodes Moseri, 1 sp. nov. 



Plate 12, figs. Jfi-57. 



The entire animal varies in length from about 100 mm. to 450 mm., ac- 

 cording to its state of contraction. All of the units arise from one and the 

 same side of the stem, although the twisting of the animal often gives one 

 the impression that this is not the case. 



The pneumatophore is small and pyriform and is situated at the anterior 

 extremity of the nectosome. Its opening is small and circular, and is situ- 

 ated at the pointed anterior end of the organ. Gas may be extruded 

 through this opening, thus enabling the animal to alter its specific gravity, 

 become less buoyant, and sink. 



The nectosome is a straight, rigid tube, which comprises about one-fifth 

 of the entire length of the animal. It is provided with from twenty to thirty 

 diametrically opposed, dove-tailed swimming-bells, the sudden and simul- 

 taneous contraction of which enables the animal to dart through the water 

 with remarkable rapidity. The gelatinous substance of these swimming- 

 bells is tough and rigid, and their cavities are capacious. Each bell (Fig. 51) 

 is provided with four radial canals, a circular vessel, and a well developed 

 velum. 



The siphosome is highly flexible and contractile and is covered through- 

 out its length with numerous tough, gelatinous, spear-head shaped bracts 

 (Figs. 55-57). The various groups of units upon the siphosome are separated 

 by free internodes. 



There are about two dozen (only six are shown in Fig. 49) feeding-poly- 

 pites (Fig. 53). These are separated from one another by long intervals. 

 Each polypite is attached to the stem by means of a short, cylindrical 

 pedicle. The body of the polypite is long, slender, and flexible, and the 

 mouth is capable of being expanded into a trumpet shape. Several small 

 rudimentary, or immature, and a single long, functional tentacle arise from 

 the side of the polypite near the distal end of the pedicle. The tentacles 



1 Named after Commander Jefferson F. Moser, U. S. N., in command of the U. S. F. C. S. 



" Albatross." 



