48 F. A. SMITT, 



Hab.: Colonia parva, a Pourtalesio ad Floridam e prof. 17 orgyarurn capta, 

 tubjmi Serpulae investit. In Mus. Brit. colonia e mari pacifico Escharce (auctt.) modo 

 erecta servatur. 



For the rounded-quadrangular form of the primary zooecial aperture, this species, 

 as it occurs in the PouRTALES-collections, more systematically would be referred to 

 the following genus Escharella, because the Hippothoan sinus of the proximal margin 

 of the aperture, in no wise here is indicated. The only alteration, that presents the 

 primary aperture. in the secondary growth, is the more rounded form, and the proximal 

 margin retains its uniform concavity. In the British Museum, however, I have seen 

 a raised stem, probably from the Pacific, which in all the other points of the zooecial 

 constitution agreed with our Floridan form, though possessing the true Hippothoan 

 primary aperture. This makes me cautious for separating the Floridan form from the 

 genus Hippothoa, and I venture to regard it as a prototypical state of the same spe- 

 cies as that from the Pacific. Further-more, it is only a little colony, in an encrusting 

 state, I have had for the examination öf the Floridan form, what, if it could be followed 

 longer, not improbably would present more developmental changes. 



The secondary raising of the zooacial aperture readily will be accounted for, if 

 we remind us the above described transverse ridge (fig. 129) över the secondary aperture 

 of the Porellina eiliata, dividing that aperture into two parts, of which the proximal 

 one will answer to the fenestra of the Hippothoa fenestrata. Otherwise, the tubiform 

 production has its nearest correspondence in the Anarthrop oridan characteristic, and, 

 in the form of the zooecia and their punctation by pores, also, it very nearly accords 

 with the Anarthrop or a minuscula, though the size is much greater. 



The acute avicularia, pointing upwards, at the side of the secondary aperture of 

 the zooecia, vary in their number, one at the one side, or two, placed symmetrically, 

 one at each side of it. 



What I here have told of the prototypical signihcance of the one form for an- 

 other, in almost the same manner refers to the genus Myriozoum, in its relation to the 

 Leieschara (Särs, mihi). If we compare the colonial form as Avell as the form of the 

 zooecia and their cancellation, all över the front, by secondary pores, of the Myrio- 

 zoum truncatum with the corresponding characters, for instance, of the Leieschara sub- 

 gracilis, we will find the closest resemblance in all that points, except the thickness of 

 the stem. But two more essential characters throw them away from each other: — the 

 first-named species has the zooecial aperture almost circular, and it wants the avicula- 

 ria. In the young and well-preserved zooecia, however, of the Myriozoum truncatum, 

 just proximally of the articulation of the operculum, we find the aperture a little eon- 

 stricted, feebly indicating what we have seen on the Mamillopora x ) and the Gemelli- 

 pora. Now, the Floridan fauna has presented us a species with that character more 

 developed, in the same time, as it possesses the lateral avicularia very much agreeing 

 with those of the Leieschara subgracilis. This Floridan species provisionally may be named 



') It iä worthy of notice, also, that the ooecia of the Myriozoum truncatum, which seem yet to be undescribed, 

 in their form reserable those of the Mamillopora cupula. 



