438 Miscellaneous. 



of the speaker hcis not been as to the species, but whether in view 

 of the difficult dcteruunation of the characteristic septa between the 

 cells, amounting, in fact, to an apparent absence of them, a new 

 genus might not be required to accommodate it. 



It was first noticed in Tacouy Creek, a small stream in Mont- 

 gomery County, Pennsylvania, at that place perhaps 50 feet above 

 tide-water. A few days after it was also gathered within tidal 

 limits in both the Delaware and Schuylkill rivers, near Philadelphia. 

 In the first-named locality it was found most abundantly in the 

 pools amongst the rapids of the stream, frequently covering the 

 tipper surface of stones, at the depth of a foot or more, to the extent oi' 

 many square inches. The erect portions of the coenoecial cells in the 

 denser parts of the colonies are about a line in height, and, standing 

 very closely, suggest a comparison with the surface of a chestnut- 

 burr. In the rivers they were found penetrating the mass of in- 

 crusting sponges, particularly Mcyenia Leidiji. 



These upright tubules are chitinous prolongations of very irre- 

 gularly inflated cells, resting in compact disorder upon the supporting 

 surface, crossed and connected in some manner not yet intelligible, 

 by meandering cylindrical rhizomes, sometimes of great relative 

 length. These are mostly terminal and simple, but are sometimes 

 branched, and frequently originate in an indifferent lateral portion 

 of a cell. The tubular prolongations are, of course, always single ; 

 the invaginated polyp retiring within the inflated portion of the 

 cell. Septa were, in a few instances, discovered in the rhizomes 

 near their insertion or connection with the inflated portion of the 

 cells. The upiight portion of those cells -which seemed to be least 

 matured were longer than those of their older neighbours, subclavate 

 or spindle-shaped and rounded at the extremities. The others are 

 cylindrical or slightly widening downwards, and shorter than the 

 former by the invagination of the terminal portion of the ectoc)'st. 

 This has the effect of producing the angular appearance of the orifice 

 so familiar in the older species ; but while that is generally quad- 

 rangular, this has frequently five or more sides. The younger celb 

 are nearly transparent, but they darken with age and become 

 somewhat incrusted with adherent particles and overgrown by com- 

 mensal parasites, Limnias, Pi/xiroh(, and the like. 



The polypides are shy, but fond of the light, and when otherwise 

 undisturbed will remain for a long time protruded in the full glare of 

 microscopic illumination. It can then be seen that the lophophore 

 is circular, without epistome, supporting ordinarily twenty tentacles, 

 taking the shape of a claret-glass and opening upwards. (Nineteen 

 and twenty-one tentacles have been doubtfully counted, while the 

 above-mentioned number is frequent ; P. Ehrcnhergi is universally 

 stated to have but sixteen.) A peculiarity of the tentacles is the 

 presence upon the outer median line of each, of a rather sparsely 

 filled series of quiescent setae, in strong contrast with the rapidly 

 moving cilia around them. 



The development of this polyp from the ovum, of which interest- 

 ing hints have been obtained, and its internal structural peculiarities 



