. Fresh-water biology. Freshwater biology. 954 FRESH-WATER BIOLOGY. 13 (10) Horizontal branches only. Cuticula delicate, colorless, hyaline. Elevated aperture-cone wrinkled and besprinkled with white. Free statoblasts nearly circular. Plumatella punctata Hancock 1850. Stock repent and open, forming long hyaline tubes that give rise to only a few, likewise repent, lateral tubes. . Var. a, prostrata. From Maine, Pennsylvania, Illinois, and Lake Erie. Stock repent, very thickly branched, completely cover- ing the substratum, which seems enveloped in thick layer of gelatinous vesicles. Var. |8, de
. Fresh-water biology. Freshwater biology. 954 FRESH-WATER BIOLOGY. 13 (10) Horizontal branches only. Cuticula delicate, colorless, hyaline. Elevated aperture-cone wrinkled and besprinkled with white. Free statoblasts nearly circular. Plumatella punctata Hancock 1850. Stock repent and open, forming long hyaline tubes that give rise to only a few, likewise repent, lateral tubes. . Var. a, prostrata. From Maine, Pennsylvania, Illinois, and Lake Erie. Stock repent, very thickly branched, completely cover- ing the substratum, which seems enveloped in thick layer of gelatinous vesicles. Var. |8, densa. Fig. 1400. Plumatella punctata, var. a. (fl) Colony two-thirds natural size, (ft) Branch much magnified. (c) Statoblast. L X 40. (After Kraepelin.) 14 (7, 15) Statoblasts, large; elliptical, but at each end drawn out into a sharp apex; broad float, hooks absent. Lophopus crisiallinus Pallas 1766. Colony shaped like a sack; erect, sometimes more or less lobed by indentations of margin, looking then sometimes like a glove. Outer cuticula layer delicate and hyaline, more incrusted at base. Polypides scattered, a group of them rising from each lobe. Lophophores with about 60 tentacles. The colony may divide along the constrictions between the lobes. Habitat, chiefly standing water, such as pools, or, rarely, slowly flowing water. Chiefly attached to plant stems. From Schuylkill and Ilhnois rivers. 15 (?) 14) Statoblasts with hooks. .... .16 16 (18) Colonies hyaline, in the form of a rosette, lobed, with horizontal tubes only Pectinatella Leidy . 17 They secrete a great gelatinous base which is common to many colonies. Aperture slightly elevated above common cocnedum. Statoblasts large and circular to subrectangular, with broad bent float and one marginal row of anchor-shaped hooks. 17 Polypides scattered orin double row along eachlobe, the gelatinous baseoften 10 to 20 centimeters thick. Pectinatella magnifica Leidy 1851. Tentacles 60 to 84 in number. Statoblasts about i mm. i
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
