1884.] NATURAL SCIENCES OF PHILADELPHIA. 21 



of large pits, six or seven feet deep, in the natural clay below the 

 burnt clay layer of one of the moui ds. These pits had long clay 

 tubes, or flues, extending from them, and there is some evidence 

 that these pits were used as places of cremation, but this must 

 be determined by further and careful study. A number of photo- 

 graphs were exhibited, illustrating the structure of the mounds 

 and the objects found in them. 



Note on Manayunkia speciosa. — Mr. Edw. Potts reported 

 having found specimens of Manayunkia speciosa Leidy, amongst 

 material collected in the Schuylkill River, above Fairmount dam ; 

 thus determining what had previously admitted of a shade of 

 doubt, the strictly fresh-water habitat of this species. In contin- 

 uation he narrated some points within his own observation, 

 supplementary to Dr. Leidy's description. 



The branchial organs (tentacles) appeared to him to be grouped 

 upon two processes on each of the lateral lophophores, eight each 

 in the upper or more dorsal groups, and six or possibly more in 

 each of the others. Beside these, there is a single pair placed 

 centrally upon the dorsal portion of the head, and a similar pair 

 opposite, which do not seem to be connected with either of these 

 groups. The whole number is therefore .32-36. The alternating 

 contractions and dilatations of the vessels conveying the green 

 blood through the dorsal pair above mentioned are very conspic- 

 uous. 



While the general appearance of this crown of tentacles, when 

 expanded, is somewhat similar to that of a poly zoan, there is a 

 noticeable difl"erence in the effect produced by the motion of their 

 cilia. In the latter a powerful incurrent bears food particles, 

 etc.. towards the mouth as a vortex ; in the former case, while 

 the motion draws these particles from without or behind the 

 circle towards the tentacles, the moment the}' pass between them 

 they are influenced by an excurrent bearing them forcibl}' away. 



This outflowing current is further shown by the fact that 

 excrementitious matters are drawn rapidly forward through the 

 tube, and ejected at its anterior extremity. 



As food, therefore, cannot be sucked into the mouth of the 

 worm, we find that it is carried in. Acceptable particles which 

 touch the tentacles are grasped by the cilia, and rapidly passed 

 down amongst tiiem in near contact with the tentacle into grooves 

 at the base of the above-mentioned processes, and thence into the 

 digestive tract. 



Beside the specimens above mentioned from the Schu^'lkill 

 River, Mr. Potts has had recently under observation a consider- 

 able number, say fifteen or twenty, from the pond near Absecom. 

 One of these, to which most of his time had been devoted, had 

 been kept for many days isolated in a microscopic stage tank. 

 While in this situation it, for some reason, left its old tube and 

 formed another, giving him the opportunity to observe the 



