CyathocormuS mirabilis n. g., n. sp. 



aiy between the thorax and abdomen the body is generally bent 

 downwards, i.e., towards the closed end of the cylinder, in 

 consequence of which the individuals overlap, so that the 

 abdomen of one zooid covers the thorax of its neighbour below on 

 the inner surface (PL I., fig. 4). For the same reason a cross 

 section passing through the branchial sac of one individual cuts 

 also the alimentary canal of one or even two individuals lying above 

 it (PL I. , fig. 3). Moreover, the median plane of each zooid does 

 not lie parallel to the main axis of the colony, but, as shown in 

 PL I., fig. 2, the zooids in a pair of rows have their endostyles 

 turned toward one another, while their dorsal edges are next the 

 space between that row and the adjacent one. In this respect the 

 arrangement of zooids in the present form exactly agrees with that 

 found in some species of Colella (=Sijcozoa, Less), e.g. C. jmklira 

 ('86, Herdman, Challenger Reports, Part 2, PI. XV., fig. 6) and 

 G. temiicaulis ('99, Herdman, Australian Museum Catalogue, PL 

 Dist. I., fig. 3). As will be described further on, the course of the 

 intestinal loop is not the same in all the individuals, but is 

 different according to the position of the zooid in a double row. 

 Those of the left side have their intestines opening into the 

 longitudinal furrow lying on the left side, while those belonging 

 to the right hand row have their anal apertures looking to right, 

 although in both cases the intestine is bent invariably to the left 

 side of the stomach (see PL, I. fig. 3). 



Test. The test is only weakly developed in the side walls of 

 the head. Here the bodies of the zooids themselves form by far 

 the greater part of the mass, while the test exists only in the form 

 of thin covering round each zooid. In some places it forms an 

 exceedingly thin partition between the zooids, so that the latter 

 seem to be separated only by a delicate membrane. Along the 

 median line of the longitudinal ridges formed by double rows of 

 zooids, however, the test substance is found to take the shape of 

 more or less thickened masses. On the outer surface of the head 

 the test forms a thin layer of nearly uniform thickness (0,035- 

 0,045 mm.) covering the anterior ends of the zooids. 



The extent and relative amount of the investing mass in the 



