ART. 14 EOSSIL AND EECEFT BRYOZOA CAZSTTJ AND BASSLER 49 



a line of very small inter junctural pores; the frontal is convex, rugose, 

 ornamented by three reniform pores arranged in a triangle. The 

 aperture is suborbicular; the peristome is very thin and accompanied 

 externally by four long hollow spines. The ovicell is enormous, glo- 

 bular, rugose, embedded in the distal zooecium, closed by the opercu- 

 lum. On the frontal a very sahent mucro is developed; it is enlarged 

 at its summit in the form of a hammer. The avicularia are small, 

 with pivot; their beak is truncated. 



,, ... f7i,(X = 0,17 mmx. 



Measurements. — Aperturei, „ .„ 



^ Ua = 0.17 mm. 



\Lz=^ 0.7 5 mm. 



Zooeciau _ __ 



1/2 = 0.50 mm. 



Variations. — The rich decoration of this species renders it very 

 difficult to study and to figure; it appears to be adapted to quiet 

 waters. The mucro is much attenuated in the convex portions of the 

 zoarium; it is, on the contrary, much developed in the concave por- 

 tions; it shows, therefore, the general rule observed in all the other 

 bryozoa. 



In the intensity of calcification the large frontal pores are obliter- 

 ated and become little visible. 



Sporadically a normal zooecium is replaced by a gigantic avicu- 

 larium of the same form as the others. Its length is also 0.75 mm. 

 Each zooecium is adjacent to two avicularia of which one is always 

 larger than the other. 



Affinities. — This new species differs very little from Tremogasterina 

 truncatorostris Canu and Bassler, 1923, from the Miocene of Santo 

 Domingo; its mucro is much more developed and its ovicell is 

 smaller. Better fossil specimens may perhaps show the identity of 

 the two species. 



Biology. — The species was in reproduction and fixation on Febru- 

 ary 29, 1884. 



On the fossil specimens all the small ornamentation which surrounds 

 the aperture disappears easily or is much attenuated. Nevertheless 

 the species is still recognizable by its micrometric dimensions and its 

 very polymorphic avicularia with truncated beak. The inter junc- 

 tural pores are often visible on the inferior noncellular face. 



Occurrence.— Albatross Station D. 2404, Gulf of Mexico; 28° 44' 

 00" N.; 85° 16' 00" W.; 60 fms.; gray sand. 

 Albatross Station D. 2136, Caribbean Sea; 17° 43' 

 40" N.; 75° 38' 25" W.; 52 fms.; coral, broken 

 shells. 

 Pliocene: Minnitimmi Creek, Bocas Island, Almi- 

 rante Bay, Panama. 

 Cotypes.— Cat. Nos. 7602, 70864, U.S.N.M. 

 58513—28 4 



