248 



Pterocella carinata Busk. 



{'nlenicella carinnta Busk, Voyage of Ballk'siiake, I, pag. 363, Catalogue of Marine 



Polyzoa, (^heilosloniala, pag. 12, I'l. VI, figs. 4, ">, (j. 



(I'l. MI, li'<. r>:\). 



The zooecia iiuadiaiigularly oval, of a loundi'd li-iangular Iraiisvorsc set'tiou, 

 lilt' basal surface consisting of two lateral halves meeting at an acute angle. 

 This surface has slightly undulating, longitudinal striie and is pro\ided with a 

 low median ridge, which in its centie rises inio a triangnlai-, s{)ine-like |)i'()cess. 

 The sternal area is generally smaller than the aperture and |)r()vi(led with 3 

 fenestra-, and the extremely small frontal sinus is occu|)ied by two rudimentary 

 spines. The anier of the aperture is semi-elli]ilic;d and its poster concave. 



The lateral chambers form on either side a triangular, acute-angled e.xjian- 

 sion, which is directeil sometimes straight outwards, sometimes a little distally 

 and the vertex or point lies at the end of the scapular chamhei-. 'i'he distance 

 between the ends of the two scapular chambers is in an unizoo'cial inlernode 

 larger nearly by a half than the length of the internode, and the two lateral 

 expansions form a distal angle of 180" — 270" with each other. The scapular 

 chamber has an extremely small mandible and is shaped like a long, narrow, 

 compres.sed tube, and the two adjoining, triangidar chambers have each a large, 

 pear-shaped opening, which is larger in Ihe su))ra-scapular chamber, the frontal 

 and distal walls of which are uncalcilied in their inner half. The i)edal clunnber 

 has a long, oval opening. The mother-zoo'cium in the bizoo-cial internode is |)ro- 

 vided with a small avicidarium, and proximally to the latter we lind as in P. ulnla 

 a narrow boundary chamber. 



The ooecium. The oa'cium as well as the gonozoo'ciuni and Ihe co\ering 

 zo<rciuin bear a close resendjlance to the corresponding parts in P. (lUita and I 

 shall accordingly limit myself to j)ointing out the most important diirercnces. On 

 the gonozooecium the sternal sinus is much less developed and occupied by two 

 likewise slightly developed spines, which, however, also have a teiuiinal i)arl bent 

 inwards and proximallj'. The most conspicuous dilTerence is however found in 

 the covering zoa^cium, which is jirovided with two lai-ge fenestra' separated by 

 a rather broad longitudinal belt. 



Form of colony. In Ihe small fragment IVom Napier, New Zealand, lliat I 

 have examined, two bizoo'cial internodes nowhere succeed each other. 



