1851.] 



265 



bed,) of 22 inches in thickness, horizontal, and but a short distance from the sur- 

 face. The shafts sunk had not yet reached any other deposit. 



No distinct vegetable impressions had been found, although Dr. L. had carefully 

 examined a large quantity of the coal. He considered the existence of true car- 

 boniferous deposits in California highly improbable. 



Dr. Leidy called the attention of the members to a pyrlform mass, about 

 three inches lono; by one and a half broad at the base, suspended in a 

 vessel of water. This, he said, consisted of numerous Polypi within their 

 Polypidom encrusting a dead branch of a tree, and was taken from a 

 similar mass one yard long, with an additional lateral branch two feet 

 long, found in a ditch below the city. The species he characterized as 

 follows : 



CRIST ATELLA, Cuv. 



CrISTATELLA MAGNIFICA, 1I-. s, 



Folypidom massive, fixed, encrusting bodies from a few inches to several feet 

 in length, by a few^ lines to 2 inches in diameter, gelatinoid, consistent, hyaline, 

 with numerous polypi upon the free surface arranged in close, irregular areolas. 



Pohjpi furnished with 2 lobes conjoined together in the form of U, enclosing 

 the mouth at the base, and having diverging from the margins from 50 to 80 sig- 

 moid tentaculae arranged at the summit in the double outline of U, with the ex- 

 tremities of the arms of the latter inclining towards each other. Lip elevate'', 

 with the base of the tentacular lobe, and the lower fourth of the inner margin oi 

 the tentaculae in the vicinity of the mouth, lake or dark rose-red colour ; oesopha- 

 gus colorless ; stomach longitudinally folded, yellowish brown; rectum dilatable, 

 hyaline, its extremity slightly projecting but retractile. 



Length from the bottom of the stomach to the top of the extended tentaculas li 

 lines. Long diameter of tentacular expanse h to 3-5th line. Length of tentaculae 

 l-40th in.; breadth 1-lOOOth in. 



Ovum lenticular, brown, enclosed at the margin by a brownish white, annular, 

 cellular sheath, l-200th in. deep upon one side, l-166th in. upon the other side, 

 furnished at its outer edge with 14 to 16 appendages l-200th in. long, terminating 

 in a double, rarely a triple booklet. Ovum with its sheath, thin, discoidal, bent, 

 l-33d in. broad, with its appendages enveloped in a hyaline, albuminoid mass ; 

 when ripe floating. 



Hahitation. Upon dead branches or twigs of trees, in ditches o'r sluggish 

 streams in the neighbourhood of Philadelphia, in shaded situations. 



Remarks. The extent of this polyp appears to be determined by that of its 

 basement of attachment. It is usually found surrounding twigs or dead branches 

 of trees which have fallen into the water, and is permanently fixed to its position. 



The surface of the polyp mass has the appearance of being covered with a 

 dense mucor from the numerous tentaculas projecting from it. Immediately be- 

 neath this is a layer having a faint roseate hue from the red colouring in the 

 vicinity of the mouth of the polypi, then succeeds a layer of a dirty yellowish 

 color, arising from the stomach of the animals, beneath which are numerous 

 opaque, white, yellowish, and brown spots, which are ova in various stages of 

 development, and finally the greater depth of the mass consists of a perfectly hya- 

 line, consistent, gelatinoid substance. 



