320 ME. A. T. JENNINGS ON A NEW GENUS OF 



On a New G-enus of Poraminifera of the Pamily Astrortizidse. 

 By A. Vaughan Jennings, F.L.S., F.G.S., Demonstrator 

 of Botany and Geology in the Eoyal College of Science, 

 Dublin. 



[Eead 6th June, 1895.] 

 (Plate X.) 

 Among the dredgings made by the ' Porcupine ' Expedition 

 (third cruise), 1869, that obtained in the Earoe Channel at 

 440 fathoms was interesting from the number of specimens it 

 contained of the large arenaceous Poraminifer Botellina laby- 

 rintJiica, Brady. 



While examining some of this material given me by the late 

 Dr. P. H. Carpenter, I found that many of the specimens o£ 

 Botellina had other Poraminifera adherent to them. 



Most of these are Truncatulina refulgens, Montf. sp., and 

 T. lolatula ; but in two cases the adherent form proved something 

 quite different — a type which has not yet, I believe, been de- 

 scribed or named. 



It consists of a tent-shaped structure, measuring about a 

 twenty-fifth of an inch in height, with slightly less diameter at 

 the base, composed entirely of sponge-spicules. The spicules 

 are very regularly arranged and closely set together, all lying in 

 the same direction, pointing from the circumference of the base 

 toward the apex. 



The spicular structure is in this case the more remarkable 

 since there can be no question as to the abundance of other 

 material at hand. The Botellina shells are constructed of coarse 

 sand-grains, and by far the greater part of the dredging consists 

 of similar material. In fact, the contrast between these delicate 

 spicular cones and the coarse sandy structure of the organism on 

 which they rest is one of the most striking instances I know of 

 the selective power in Protozoa. 



At the base the shell is fixed to the rough surface of the 

 Botellina by a small amount of a white, doubtless calcareous, 

 cement ; but in the walls there is very little interstitial matter. 



In the dry specimen the apex of the cone is closed; but I 

 should think it probable that in the living condition the spicules 

 were more or less mobile, so as to separate to some extent at the 

 top, and ^llow a free passage of the protoplasm to the exterior. 



