233 



Scuticella sacculata Busk. 

 Catenicella sacculata Busk, Challenger, Zoology, Vol. X, Part I, pag. 12, PI. 1, fig. 7. 



(PL XII, fig. 2 a). 



The zocecia, the surface of which is provided with a number of very small, 

 widely scattered pores, are long, slender and constantly increasing in breadth 

 from the very narrow proximal end towards the aperture, from which the lateral 

 margins again converge distally. The aperture has a slightly concave proximal 

 margin, and the extremely small sternal area has but a single, small, round 

 fenestra proximally. The sternal sinus is occupied by three spines, of which the 

 proximal, rudimentary one is solid, w^hile the two others, which meet in a sutural 

 line, have an inner cavity opening outwards through a small pore near the dis- 

 tal margin. The sternal cryptocyst lamina has an arch-shaped proximal margin, 

 which is clearly visible on the frontal surface through the only opening of the 

 latter. 



The lateral chambers. The scapular chamber is everywhere except on the 

 adzocecial side of the daughter-zooecium developed as a medium-sized, rather 

 strongly projecting and somewhat ascending avicularium, which is directed out- 

 wards and slightly basal ly. The other chambers are wholly membranous and 

 bounded only by low calcareous ridges. The supra-scapular one, of which but 

 an extremely small part is seen on the basal surface, on the frontal surface 

 almost reaches the distal margin of the aperture and the outer end of the roof 

 of the avicularium. The infra-scapular one, which is directed laterally, is rather 

 large and of an oblong, quadrangular or pentagonal form. It is separated by a 

 small intermediate space from the very long and rather broad pedal chamber, 

 which is situated a little more frontally and occupies about two-thirds of the 

 whole length of the zocecium. Along its middle we find a row of 6 — 7 rosette- 

 plates. The mother-zooecium is provided with a long, narrow, infra-scapular ad- 

 zocecial chamber. 



Ocecia have hitherto not been found. 



This species may be regarded as a transitional form between Scuticella and 

 Catenaria. I have been able to examine a small fragment of it, for which I owe 

 thanks to the direction of the British Museum. 



Costicella n. g. 

 The sternal area, which is provided with 4—14 fenestrse, disposed in a curved 

 line, and with a cryptocyst lamina of a similar outline, is to a greater or smaller 

 extent formed by a number of generally hollow spines, springing from the sternal 



