226 ROTIFERA 



Fam. 24. Seisonidae : Seison Grube ; Paraseison Plate ; Saccobdella Van 

 Beneden and Hesse. 



Habits. The habitat of Kotifers is well known to the student 

 of pond life. Every dip from a greenish pool will give us a 

 supply, if there be not an excessive contamination by manure ; 

 and such pools give us some of the largest and most beautiful 

 forms, such as Hydatina and Brachionus, swimming about among 

 the fibrous Algae and feeding on the organic debris among them. 

 Almost any organic infusions freely exposed to the open air will 

 yield Ploima shortly after the active putrefaction is completed. 

 The finer water -weeds yield most of the beautiful tubicolous 

 forms. A whole group of species and genera are quasi-pelagic 

 in fresh and salt water, constituting a large proportion of the 

 " plankton " or floating life near the surface ; and some of these 

 are found in deep water or in the depths of the lakes. Among 

 them are the Asplanchnidae, Triarthridae, and Anuraeidae. A 

 number of Loricates, such as Notholca and Eretmia, are armed 

 with long spines, which doubtless rendei floating easier. 



Among tubicolous forms Conochilus volvox and Lacinularia 

 racemovata have this pelagic habit, forming floating globular or 

 ovoid colonies, and two species of Floscularia also float freely in 

 their tubes. 



The following forms occur in salt or brackish water, those 

 marked with an asterisk (*) also occurring in fresh water : 



Floscularia campanulata.* Melicerta tubicolaria* Rotifer citrinus.* 

 Discopus synaptae. Synchaeta baltica, S. monopus, S. apus, S. tremula,* S. 

 longipes, S. tavina. Asplanchna girodi.* Asplanchnopus syringoides. 

 Hexarthra polyptera. Notommata naias, N. reinhardti. Proales decipiens. 

 Furcularia forficula* F. gracilis, F. reinhardti, F. marina, F. neapolitana. 

 Diglena catellina,* D. suilla, D.putrida. Pleurotrocha leptura. Distemma raptor, 

 D. marinum, D. platyceps.* Bothriocerca longicauda. Polyarthra platyptera* 

 Triarthra longiseta.* Rattulus calyptus. Diurella marina, D. brevidactylus, 

 D. brevis. Diaschiza fretalis. Euchlanis luna. Monostyla quadridentata, M. 

 lunaris. Colurus amblytelus, C. uncinatus,* G. dactylotus, C. coelopinus, C. pedatus, 

 C. rotundatus, 0. truncatus, G. caudatus.* Mytilia tavina. Pterodina clypeata. 

 Brachionus bakeri* B. mulleri. Anuraea valga,* A. Uremis* A. aculeata,* A. 

 tecta,* A. cochlearis* Notholca striata,* N. scapha* N. thalassia, N. spinifera, 

 N, inermis, N, jugosa, N. rhomboidea. Seison grubei, S. annulatus. Paraseison 

 asplanchnus, P. nudus, P. proboscideus, P. ciliatus. Discobdella nebaliae. 



Thus about seventy species are recorded as marine. Synchaeta 

 baltica is truly pelagic, and contributes to the phosphorescence 

 of the ocean. 



