FLORIDAN BRYOZOA. 39 



on these stems, I have measured to be about 0,09 mm. Whith the development of the 

 ocecion, we do not find the apertural spines, and the ooecion, from its circumference, is 

 covered by a layer of calcification, leaving a rounded space of its front more uncovered. 

 The rounded avicularia, directed downwards, hold their place in the middle of the front 

 of the zooecia, but, irregular as is their development, very often they are missing. From 

 the surface of the stem they are raised with that point looking downwards (proximally), 

 Which, in the acute avicularia, answers to the tip of the rostrum. Thus, their aperture, 

 in its oblique position against the surface of the stem, looks upwards a little. As to the 

 size of this aperture, in its varieties, very often, in its breadth, it nearly approaches that 

 of the zocecial apertures. 



Very unlike this, the Gemellipora striatula is going on in its calcification of the 

 wall of the colonial organs. This form, in the single colony I have had for examination, 

 remains very thin and rather closely perforated by its quicuncial primary pores. The 

 interstiees between these pores, in an undulating manner, almost as we see it on the 

 Homeroe '), are very delicately striated. The zooecia, furthermore, are a little more 

 coarsely marked by transverse furrows, and on the front of the ooecia, from each side 

 of the aperture, usually we find a longitudinal depression. All the colonial organs are 

 depressed, very little convex on their front side. The aperture of the zocecia differs 

 from that of the preceding form, essentially, in its size: its breadth I have measured 

 to be about 0,06 mm. At the distal end of the ooecia, an avicularium is developed, 

 with an elliptical aperture, the rounded mandible closing its proximal part. In want 

 of the ooecia, at the distal end of the zooecia we find an avicularium with a similar 

 aperture. 



In reference to the relations, which we know to exist between other bryozoa, 

 more nearly related to each other, if we try to inquire into the manner, in Avhich the 

 last two Gemelliporce are connected, in accordance with the laws, that are followed, 

 generalfy, in their increase, by the Chilostomata, the form of the colony as well as 

 the size and flatness of the colonial organs and their less degree of calcification show 

 the Gemellipora striatula to be of a lower stage of cheilostomatous development than 

 the G. glabra. This again, through the form of its zooecia, especially that of the 

 younger, utricular, ones, clearly shows the tendency of the Myriozoidan type, also, 

 towards the Celleporine configuration as the general end-point for the Escharine devel- 

 opment. But in the same time, these zooecia retain their apertural spines, which, ge- 

 nerally, with a higher degree of chilostomatous development, for a more or less part, 

 are cast away. Thus, in this respect, the Gemellipora glabra stånds nearer the flustrine 

 origin of the escharine development. For a more accurate determination of their true 

 relation to each other, a complete series of developmental changes of G. glabra, from 

 the first zocecia at the origin of its colonies, as well as a greater richness of specimens 

 of the G. striatula will be needed. With our present knowledge, the last-named form, 

 most probably, seems to be a degenerated variety of the same type as the G. glabra. 



') Öfvers. Vet. Akad. Förh., 1866, Tafl. VII, %. 13. 



