Fewkes.] sya [November 5, 
inferior side of the second swimming bell can be distinguished in Diphyes 
Sieboldti where two bounding ridges are continued on into two pro- 
jections. The section thus marked out is not a spheromere, for it has 
no tube in it. It is easily to be recognized in Epibulia (Galeolaria), 
where it has homologous circular plates which can almost close over 
the entrance to the bell. In the two larger nectocalyces of Praya the 
difference lies rather in the enlargement of the superior spheromere 
than in any ridges with similar appendages. In the larger nectocalyx 
of Abyla I think there is nothing to represent the pair of appendages 
to the medial canal (Mantelgefasse) which one finds in Agalma Sarsii, 
and one of which is represented by the gastric cavity in the upper, 
smaller bell. In Praya diphyes,+ both of the large bells have 
these appendages present; in Praya maxima, however, it is only in 
the smaller nectocalyx that this Mantelgefiiss exists; a condition, as 
far as this is concerned, not unlike that in Abyla. Among Physo- 
phoridae the difference between superior and inferior spheromeres even 
in Apolemia is very slight. In Agalma, Agalmopsis (Stephanomia) 
Halistemma, Stephanomia (Forskalia), and Physophora it is very 
small. I would limit this inferior side of the bell in the genus Abyla 
by the tubes which pass to the circular tube. The smaller ridge 
which lies midway between the two larger, under which the tubes have 
such a modification, would then lie medially in this side. About 
a plane passing through tus line, or indeed any longitudinal line in 
the larger swimming bell of Abyla, no bilateral symmetry can be said 
to exist as is the case in the tubes of the nectocalyx of many other 
Siphonophores. 
I do not know what toconsider the homology of this secondary tube 
in Abyla. It does not seem to be homologous to aside branch of a radial 
tube asin Willia, or if it is, that does not explain the other secondary 
branch already described, as also its existence in only onesegment. A 
fifth chymiferous tube is a thing unknown in the nectocalyces of 
Siphonophorae. The secondary tube has some likeness to that con- 
necting branch marked with a little star in Leuckart’s figure, passing 
over the superior part of the anterior bell of Epibulia (Galeolaria). 
1 In my studies at Villa Franca I took P. maxima, P. diphyes, and a third species 
whichI do not know. I have followed Gegenbaur in his distinction between these 
twospecies. Gegenbaur. Beitrige zur niheren Kenntniss der Schwimmpolypen. 
p. 19.—Leuckart, Zur nahern Kenntniss der Siphonophoren von Nizza. p.40. For 
synonomy see Keferstein und Ehlers. Zoologische Beitrage pp. 20-26. © ‘ 
