154 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



THALAMOPORELLA (?) INSOLITA, new species 



Plate 17, fig. 4 



Description. — The zoarium is free and cylindrical. The zooecia 

 are distinct, united by their mural rim, large, elongated, lozenge 

 shaped; the mural rim is thin and salient; the cryptocyst completely 

 surrounds the aperture and is finely granulated. The aperture is 

 semielliptical, transverse; the peristone is thin and very salient; there 

 is a kind of lyrula in the aperture. On the cryptocyst there are above 

 the aperture three small pores in a triangle and two, large salient 

 avicularia, elliptical, transverse with pivot; on each side of the aperture 

 are two fosettes and above the aperture a small median avicularium 

 and two large opesiules. 



Measurements . — 



. fk = 0.17mm. „ . 1X2= 1.05 mm. • 



Aperture 7 Zooecia, _ _ 



\la = 0.12 mm. [£2 = 0.85 mm. 



Affinities. — The figured specimen only has been found; it was dead 

 and we have been able to make no useful observations permitting us 

 to classify the species exactly. This is an entirely strange animal to 

 which we are calling attention. 



Occurrence.— D. 5574. Simalac Island, north of Tawi Tawi; 5° 30' 

 45" N.; 120° 07' 57" E.; 340 fathoms. 



Holotype.—C&t. No. 7958, U.S.N.M. 



Genus THAIROPORA MacGillivray, 1882 



The ovicells are unknown. The opesiules are very unequal in size 

 and the smaller one may disappear. The larger opesiule differs from 

 that of Thalamoporella in being transversely slit-like, often oblique 

 and a number of denticles commonly project across it from its proxi- 

 mal wall. The cryptocyst is transversely depressed at about the 

 middle of the zooecium and the polypide tube commences at a great 

 distance from the frontal membrane, rising steeply to the orifice. 

 The cryptocyst is usually divided into four "segments" separated by 

 ridges; a proximal and distal portion extending across the whole 

 width of the zooecium, and two lateral portions between them meeting 

 in a median suture. The avicularia are the pointed type, in the species 

 of which satisfactory descriptions have been given (Harmer 1926). 



Genotype. — TJiairopora {Membranipora) dispar MacGillivray, 1869. 



Range . — Recent. 



The zooecial structure is so close to that of Thalamoporella that 

 Levinsen, 1909, reunited the two genera in a single one, but Harmer, 

 1926, noting that the ovicells arc unknown in Thairopora, preferred to 

 separate them. 



