No. 6. — The Stomach and Genital Organs of Astrophytido. 
jy THEODORE LYMAN. 
(Published by Permission of the Lords Commissioners of the Treasury, and of the 
Hon. C. P. Patterson, Supt. U. S. Coast Survey. ) 
In typical Ophiurans, the mouth, just above the teeth, opens by a 
round contractile aperture (the stomach-sphincter) into a large flat- 
tened sack (the stomach), which spreads over the bases of the arms and 
into the interbrachial spaces. This stomach is commonly separated by 
a greater or less space from the outer disk-wall, to which it is suspended 
by delicate threads. Although sometimes a little wrinkled or pleated, 
it is usually simple, and destitute of pouches, convolutions, or cœcal 
appendages. Such is the form that runs through the whole series of true 
Ophiurans, so far as I know them, not excepting the archaic Ophiomu- 
sium. Between the stomach and the disk-wall lie the reproductive or- 
gans. Proceeding inward from a genital opening there is, first, an 
elongated bag (bursa, Ludwig), which is a fold or bubble of the lining 
membrane, and which, by minute holes, communicates with other little 
bags, simple or contorted, the egg- or spermatozoa-bearing tubes (ovarial 
Schläuche). It will be noted that these bursæ, as Ludwig has shown,* 
are closed sacks, having no communication with the body-cavity, and in 
this respect hold the same relation to the genital openings that the 
stomach holds to the mouth. 
A similar structure might reasonably have been looked for among the 
Astrophytons, which, despite their curiously branching arms having 
special joints and a peculiar covering, are, especially in the young 
stage, very closely allied to the Ophiurans. Indeed Ophiuridæ are in 
some sort connected with Astrophytidæ, albeit in no straight or un- 
broken line, by such genera as Ophiomyxa, Ophiochondrus, Hemieuryale, 
Astroschema, Astrogomphus, and Astroenida. 
When, therefore, I made a first section of a fine Gorgonocephalus 
Pourtalesii, brought back by the “Challenger,” and whose swollew disk 
indicated a gravid individual, I expected to find a general arrangement 
of organs quite similar to that already known in such genera as Ophio- 
* Hubert Ludwig : Beiträge zur Anatomie der Ophiuren. Zeitschr, für Wissen- 
schaftl. Zoologie, Bd. XXXI., 1878. 
VOL. VILI — NO. 6; 
