INFUSORIA 



57 



3. LEMBITS Cohn. Body elongate, with a long caudal bristle ; mouth 

 in the middle with the oral groove leading to it from the forward end: 

 in decaying plants; 3 species; marine. 



Fig. 93 



Fig. 94 



Fig. 95 



Fig. 93 Lembadion tullinum (Conn). Fig. 94 Pleuronema chrysalis (Calkins). 

 Fig. 95 Lembus injusionum (Calkins). 



L. infusionum Calkins (Fig. 95). Body lancet-shaped, with a taper- 

 ing anterior extremity; a row of contractile vacuoles extends from the 

 hinder end forward; length .07 mm.: Woods Hole. 



FAMILY 8. OPALINIDAE. 



Mouth absent; body oval or elongate: 6 genera, parasitic in the 

 Anura and in worms and mollusks. 



1. OPALINA* Purkinje and Valentin. Elliptical Infusoria living 

 parasitic in the rectum of frogs and toads; 13 species. 



O. ranarum Pur. and Val. (Fig. 96). Body flattened; 

 many contractile vacuoles; length .6 mm.: in frogs and 

 toads. 



2. ANOPLOPHRYA Stein. Body elongate: in the di- 

 gestive tract of marine annelids and on the gills of 

 crustaceans; occasionally free-swimming. 



A. branchiarum St. Length .1 mm.; body flask- 

 shaped: Woods Hole; free-swimming. 



ORDER 2. HETEROTRICHIDA. 



Body with uniform ciliation and an adoral zone along the oral 

 groove consisting of cilia fused together to form membranelles : 7 families. 

 Key to the families of Heterotrichida here described: 



a t Body not in a cup. 

 &! Body not with a crown of long cirri, 

 c?! Body not funnel or trumpet-shaped. 



rf, Body elongated 1. PLAGIOTOMIDAE 



d 2 Body usually oval with a triangular oral groove 2. BURSABIIDAE 



c 2 Body funnel or trumpet-shaped 3. STENTOBIDAE 



6 2 Body with a crown of long cirri 4. HALTERIIDAE 



a 2 Body in a cup 5. TINTINNIDAE 



* See "Opalina," by M. M. Metcalf, Arch. f. Prot., Vol. 13, p. 195, 1909. 



