18 



BULLETIN 104, UNITED STATES NATIONAL MUSEUM. 



Description. — -Test free, typicall\' consisting of a central inflated,, 

 subspherical or irregular bod}' with numerous short arms radiating 

 from various points of the surface, sometimes irregular and elongate, 

 irregularly branching; wall tliin, composed of a single layer of rather 

 coarse sand grains with a brownish cement, firmly joined, exterior 

 irregular, arms in the subglobular form usually ending in single cu'- 

 cular orifices; those of the elongate form usually with one or more 

 chitinous tubes, bifurcating at the tip. 



Length of the elongate form, up to 6 mm.; the diameter of the 

 subglobular form rarely exceeding 1.5 mm. 



Distribution. — Brady records this species from four Atlantic sta- 

 tions, south of the Rockall Bank, 1,215 fathoms; off the west coast 

 of Ireland, 816 fathoms; from the warm area of the Faroe Channel, 

 532 fathoms, and southeast of Pernambuco. Brazil, 350 fathoms. 

 Flint records it from the east coast of the Ignited States and from 

 near old Providence Island in the Caribbean. I have noted it from 

 12 stations in the Albatross material from the region of Georges 

 Banks to Cape Hatteras, stations ranging in depth from 515 to 2,045 

 fathoms and bottom temperatures from 34.4° to 39.7° with a single 

 station 45° F. 



Practically all the material off the shores of the United States is 

 the subglobular form with the short radiating arms figm'ed by FUnt 

 from the same region. The elongate form may prove to be a different 

 species, as it has very different characters in the bifurcating arms, 

 etc. I have not, however, had an opportunity to study any except 

 dried material and in this the arms are lacking. 



Rhabdammina cornuta — ■material examined. 



RHABDAMMINA CORNUTA H. B. Brady, var. SPICULOTESTA, new variety. 



Description. — Test differing from the typical form in the material 

 used in the construction of the test, sponge spicules being used 

 almost exclusively, the shape of the body and the angles of the arms 

 being largely determined by this fact, the spicules being unadapted 

 to a curved surface. 



