2i6 Papers from the Marine Biological Laboratory at Tortugas. 



wart-like prominences; in tiie smaller size of the ooecia; in the much slighter 

 development of the rostrum, which never rises much above the avicularium ; 

 and in the more procumbent position of the rostrum, which projects forward 

 over the orifice. The form of the orifice is, as stated by Smitt, very similar 

 to that of albirostris, but (as Busk points out) this form is common to a 

 number of species. Small hinge denticles are sometimes present. Smitt 

 figures the species as having from 3 to 6 oral spines. There is scarcely any 

 indication of these in the specimen in my possession. The oral avicularium 

 is usually rounded, but occasionally the mandible is obtusely triangular. 

 No other avicularia are present. 



One colony 0.25 inch in diameter incrusting a shell at low tide. 



Smitt records it from Pourtales's collections at 9 to 60 fathoms. 



Holoporella magnifica n. sp. (Figs. 22 and 23.) 



A very coarse species with very large zooecia and orifices large enough 

 to be distinguished readily by the naked eye. Taken at 10 fathoms incrust- 

 ing a sponge and a very small colony on a dead shell at the same depth. 





s 



rh 



Fig. 22.— Holoporella magnifica n. sp. Young zooecium at edge of colony, showing manner of growth. 



Rostrum and rostral avicularium not yet developed. 

 Fig. 23. — The same. Highly calcified portion near center of colony, showing one deeply immersed and three 



erect superficial zooecia, independent avicularia of two sizes, and the rostral avicularium. 



Zooecia large, procumbent at the growing edge, erect and irregular at 

 the center of the colony. Imperforate except around the edge, where there 

 are large pores, often coarsely cancellated between the cells in the middle 

 of the colony. Very heavily calcified, even in young cells. The orifice is 

 much as in H. albirostris, except that it is much larger. The peristome is 

 very thick and broad, slightly raised all around the orifice (when ooecia are 

 present it extends over them in later stages of growth). The rostrum is 

 small and low, projecting so slightly over the orifice as to scarcely hide the 

 posterior margin in any case. On one side of the rostrum is placed a large 



