332 



of this there is a large, obliquely ascending projection, with its level surface 

 turned towards the ascopore. The distal half of each zooecium is provided with 

 3 — 4 elongated, multiporous pore-chambers. 



The ooecia, which are endoooecial, but nevertheless prominent on the surface 

 of the zooecium, are broader than high and provided within the membranous 

 ectoooecium with a cryptocyst layer, which proximally to the aperture may run 

 out into an irregular projection. There is a spine on each side of the aperture. 



The heterozooecia, which occur in pairs on each zooecium, are in the form 

 of vibracula and are situated one on each side of and a little proximally to the 

 aperture. The oval or pyriformly oval frontal area is as in E. vulgaris and E. pes 

 anseris provided with a distal concavity for the reception of the long, narrow, 

 dark-coloured flagellum, which from a triangular proximal part terminates in a 

 point. 



Of this species I have examined a single, extremely small, incrusting colony, 

 which shows superficial budding; Syracuse, rocky bottom, 15 — 25 fm. (Dr. H. J. 

 Hansen). 



Arthropoma n. g. 

 Schizoporella Hincks p. p. 



The zooecia lack a covering-membrane and are provided with scattered pores. 

 The aperture, which has a distinct but low vestibular arch, is provided with a 

 narrow, deep sinus, and the well-chitinized operculum consists of two parts con- 

 nected by an articulation (i. e. a more weakly chitinized connecting part), a 

 principal part, which is provided with two muscular dots and an accessory 

 part, which occupies the sinus. Avicularia may be present. The ooecia consist of 

 a calcified endoocecium without pores and a membranous ectoooecium. The dis- 

 tal half of each zooecium with three multiporous rosette-plates (often only groups 

 of small, uniporous rosette- plates) or three pore-chambers. 



To this genus belong A. (Schiz.) Cecili Aud. and A. (Schiz.) circinata Mac Gill. 

 Whilst the rosette-plates in the former may undergo a faii'ly considerable varia- 

 tion, even in zooecia of the same colony, the elongated groups of small, uniporous 

 rosette-plates being sometimes quite open, sometimes surrounded by a more or 

 less projecting edge, we find in the latter species small pore-chambers with a 

 single row of pores in each. Whilst A. Cecili in contrast to A circinata as a rule 

 has neither spines nor avicularia, a remarkable, spine-bearing, independent avi- 

 cularium, the mandible of which is provided with a similar accessory part as 

 the zooecial operculum, has been found by Kirkpatrick^ in a variety of the 



1 48, p. 21. 



