THE ANATOMY OF THE MADREPORARIA. 
585 
5. Septa, when present, always lie between a pair of mesen- 
teries (entosepta), sometimes also in the spaces intermediate 
between pairs of mesenteries (exosepta). 
6. Tentacles may be exocoelic as well as entocoelic, but 
exosepta may be present without corresponding tentacles. 
The present classification of the Madreporaria is admittedly 
unscientific. I have therefore laid stress on what may perhaps 
seem the trivial point of the relations of septa and tentacles 
to the mesenterial spaces, as it is probable that, since the 
morphological differences of the whole group of Zoantharia 
hexacoralla are very slight, such structural variations might 
be useful for a new classification; which, if based upon the 
relations of polyp to skeleton, will be on a far sounder 
foundation than the present one, which rests upon the skeleton 
alone. 
Flabellum patagonichum (Moseley). 
This is an imperforate Madreporarian, belonging to the 
family Turbinolidm. As Moseley ( 11 ) has given a full descrip- 
of the specific characters of the corallum in his “ Challenger ” 
Report (to which reference should be made for figures of the 
complete calyx), only a few of them will be mentioned here. 
i. The corallum is solitary and conical, the apex of the 
cone forming a pedicle by which the polyp is attached when 
young; in the adult the pedicle becomes obliterated, and the 
coral free (vide figs. 2, 3, Pe.). The outline of the mouth of 
the calyx is oval (fig. 1). There are four orders of septa, all of 
which are entocoelic ; six of the first order, which meet in an 
elementary form of columella; six of the second, which are 
nearly as long as the primary septa; twelve of the third, and 
twenty-four of the fourth order. In some specimens the full 
number is not developed. The corallum is about 2 cm. high 
in a well-grown specimen; and the longer axis of the calyx 
mouth about 2£ cm., the shorter axis 2 cm. in length. 
Along the lines which correspond on the exterior surface of 
the theca with the attachments of the septa on the interior, are 
shallow but distinct grooves running from lip of calyx to tip of 
