. Fresh-water biology. Freshwater biology. 334 FRESH-WATER BIOLOGY 4 (27) Pharynx simple 5 S (20) Protonephridia with one principal branch, median dorsal in position. Family Catenulidae . 6 Without eyes but with ciliated pits, non-pigmented light-refracting organs, and in one genus a statocyst. The mouth Hes on the ventral side of the anterior end. The pharynx opens into the anterior end of the intestine. Asexual"reproduction by budding, thus forming chains of zooids, known for most species. Testes in front of ovary. Both testes and ovary may consist of one or more lobes. (7) With one sta
. Fresh-water biology. Freshwater biology. 334 FRESH-WATER BIOLOGY 4 (27) Pharynx simple 5 S (20) Protonephridia with one principal branch, median dorsal in position. Family Catenulidae . 6 Without eyes but with ciliated pits, non-pigmented light-refracting organs, and in one genus a statocyst. The mouth Hes on the ventral side of the anterior end. The pharynx opens into the anterior end of the intestine. Asexual"reproduction by budding, thus forming chains of zooids, known for most species. Testes in front of ovary. Both testes and ovary may consist of one or more lobes. (7) With one statocyst and pre-oval circular groove Catenula. But one species supposed to occur in America. Catenula lemnae (Anton Duges) 1832. Length of single specimen i mm. Rarely 2 to 4 or 8 zooids in a chain. DeUcate, white thread-like. Head region set off by a circular groove lined with long ciha. Intestine short and not continuous through chain of zooids. Graff regards the European species C. lemnae as prob- ably identical with the species which was collected in the vicinity of Philadelphia and very incompletely de- scribed by Leidy under the name Anortha gracilis. Until further collections of the Philadelphia form have been made this must of necessity be a matter open to question, and C. lemnae be admitted to the list of Ameri- can species tentatively. Fig. 591. Catenula lemnae. M) anterior end: 6, brain; eg, cili- ated groove; w, mouth; j/, statocyst. X 75. (After von Graff.) {B) Chain of two zooids. X 30. (After Mrazek.). 7 (6) Without statocyst or pre-oral circular groove. With ciliated pits. 8 8 (19) CiHated pits well developed. Without proboscis. Stenosiomum. 9 9 (18) Head region not at all or only slightly set ofi from rest of body. 10 10 (17) Integument colorless n :i (14) Wall of digestive tract free from pigment 12. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these ill
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
