Fewkes.] 318 oe [November 5, 
would be readily discernable in the structure of the pebbles, but I can 
find nothing of the kind. The sand grains are as round as those 
upon the sea shore. 
Tue TuBES IN THE LARGER NECTOCALYX OF ABYLA 
PENTAGONA. By J. WALTER FEWKES. 
The course of the chymiferous tubes in the larger swimming bell of 
Abyla pentagona has never been satisfactorily described. Leuekart 
gives the best description of the very peculiar form of these tubes in 
the smaller bell, but simply says of them in the larger that “ he could 
with certainty follow them to the circular vessel.”! In the drawing of 
this nectocalyx, which he gives in his Zoologische Untersuchungen, 
Taf. 111, fig. 1, he represents four of these vessels as passing directly 
from a common origin to the circular tube just as is the case in a 
simple hydroid Medusa. 
Neither figures nor descriptions by other writers give a correct idea 
of the course of these tubes. In most cases, as in the figures of 
Abyla in the Oceanic Hydrozoa of Huxley,? they are wholly omitted 
both in the upper and lower nectocalyces. In one figure Kolliker ® 
gives a correct idea of their origin, but the drawing was only made 
to illustrate the structure of the smaller bell, so that the peculiar 
modifications in the course of these tubes in the lower part of the 
larger bell were not given. Of Vogt’s + description, Leuckart ® says, 
“‘ Die Gefasse der hintern Schwimmglocke, die von Herrn Vogt nicht 
erwahnt werden, konnte ich u. s. w.” 
Gegenbaur gives a good description of the branched vessel which 
I have lettered e+ and c 1. 
As is well known the under side of the lower nectocalyx of Abyla, 
as it naturally floats in the water, forms a groove protected on either 
side by a ridge. From the side of the smaller of these ridges is 
formed a plate under which the stem of the Abyla is withdrawn. 
Kolliker ® gives a schematic drawing of the relation of this plate 
to the side of the bell. The existence of this plate causes certain 
1 Zur nihern Kenntniss der Siphonophoren von Nizza, p. 14, 1854. 
2 Oceanic Hydrozoa, pl. II, fig. 1, 12, 2, 25, 
8 Schwimmpolypen oder Siphonophoren von Messina, Tab. X, fig. Ds 
4 Sur les Siphonophores de la Mer de Nice. 
5 Siphonophoren von Nizza, p. 14. 
6 Neue Beitrige zur niheren Kenntniss der Siphonophoren, p. 355. 
