26 



BULLETIN lOi, UNITED STATES NATIONAL MUSEUM. 



a narrow contracted mouth-opening. Extraneous matter of body wall consisting for 

 the most part of sand grains, but at the oral extremity composed almost solely of 

 fragments of sponge spicules longitudinally arranged. 



Marsipella cylindrica — material examined. 



MARSIPELLA SPIRALIS Heron-AUcn and Earland. 



Plate 9,%. 7; plate 10. iigs. 6. 7. 



Marsipella spiralis Heron-Allen and PvArland. .Toiirn. Roy. Micr. Soc, 1912, 

 p. 387, pi. 5, fig. 7: pi. 6, figs. G, 7. 



The original description is as follows : 



Test free, monothalamous, consisting of an undi\'ided tube, which is built up of 

 minute fragments of sponge spicules embedded in a light-gray cement, and arranged 

 transversely to the long axis of the tube. The spicules are built in a single layer, 

 and have a distinctly spiral arrangement when the specimen is examined either as 

 an opaque object or in a balsam mount. Viewed as an opaque object under a 12 

 mm. objective. Marsipella spiralis looks exactly like a piece of white string. 



The protoplasm is dark brown in color and appears to run the entire length of the 

 tube. 



Marsipella spiralis is one of the most interesting species we have met. The use 

 of sponge spicules, either entire or fragmentary, as building material is of frequent 

 occurrence in the Foraminifera, but we know of no other species, except its near 

 relative, Marsipella eylindrica (Brady) and Technitella lerjumen (Norman), in which 

 sponge spicules are employed in a manner or for purposes which in any organism of 

 higher development than the P"'oraminifera, would presuppose "intelligence" on the 

 part of the builder. 



The sponge spicules employed by Marsipella spiralis are almost without exception 

 fragments. They are selected of practically uniform length, 0. OG-0. 1 mm., and 

 arranged at angles between 30° and 45° around the tube. The spiral is always left- 

 handed. It is ob\'ious that the strength of the tube is greatly increased by the spiral 

 arrangement of the spicules; indeed, Marsipella has made the same great discovery 

 as the man who first observed that a twisted string Avas stronger than an untwisted 

 wisp of fibers. 



Marsipella spiralis is confined to a limited area, so far as our observations go. It 

 occurs rarely in a rich foramini erous mud dredged by the Goldsecl-er in the North 

 Sea (Haul 145, Station IXB, depth ;530 meters), and an occasional specimen is to be 

 found at adjacent stations, especially Station IX (61° 34^ N.; 2° 4' K., 390 meters). 

 No specimen has yet been found sho\nng definite initial or final portions of the tube, 

 all being more or less fragmentary; but the fact that nearly all the fragments were 

 liATlng when dredged, as was proved by the presence of protoplasm in the tube, seems 

 to show that the tube may grow indefinitely, and that injuries to the extremity of 

 the tube do not effect the life of the animal. The tube is doubtless flexible when 

 living, like Bathysiphon fdiformis (Sars). The fragments vary from 1 to 4 mm. in 

 length. The average external diameter of the tube is 0.08 nun. 



