7l8 ORDER PERITRICHA. 



Genus XIII. THURICOLA, S.K. 



(Greek, t/mris, door ; coio, to inhabit.) 



Animalcules and loricas as in Vaginicola^ but the latter structure having 

 hinged to its inner wall a simple or complex valve-like apparatus, which 

 closes obliquely after the manner of a door when the animalcule contracts, 

 and protects it from intrusion from without. Inhabiting salt and fresh 

 water. 



This new genus is established by the author upon the Vaginicola valvata of Dr. 

 Strethill Wright, to which is added the Cothurnia operailata of Gruber and a fresh- 

 water type, apparently identical with the Vorticclla folliailata of Miiller, found by 

 recent investigation to exhibit a remarkable modification of the characteristic door- 

 like valve. 



Thuricola valvata, Wright sp. Pl. XL. Figs. 4 and 5. 



Lorica subcylindrical, truncate posteriorly, four or five times as long 

 as broad, bearing internally at some distance from its aperture an oval 

 valve-like organ, which, falling down when the animalcule retreats, effectually 

 protects it from intrusion from without ; body hyaline, capable of extension 

 for about one-third of its total length beyond the orifice of the lorica. 

 Length of lorica 1-200". Hab. — Salt and fresh water. 



This animalcule, originally described by Dr. Strethill Wright under the title of 

 Vaginicola valvata, was discovered by him in sea-water and is usually recorded as a 

 strictly marine form. D'Udekem * reports, however, a species from fresh water that 

 is apparently indistinguishable from this type, and an identical animalcule has been 

 frequently observed by the author. In accordance with the description of its 

 original discoverer, the characteristic valvular apparatus is of an ovate shape and 

 horny consistence, developed within and covered by a fleshy plate, which is attached 

 by one edge and continuous with a pellicle that lined the entire cavity of the lorica. 

 This fleshy plate alone forms the hinge-joint to the horny valve, and is consequently 

 separated and absent from the dead and empty tubes. In specimens recently 

 received from Mr. John Hood of Dundee, the presence of a hning membrane in con- 

 nection with the operculum as above reported, and similar to that figured by Gruber 

 of Thuricola opoxulata, was found to exist. Excepting for the presence of this 

 peculiar valve, the animalcule and its tube in the present species closely approxi- 

 mates in form and size the fresh-water Vaginicola crystallina. 



Thuricola foUiculata, Mlill. sp. Pl. XL. Figs. 6-8. 



Lorica subcylindrical, rounded and slightly widest posteriorly, about 

 four times as long as broad ; valvular apparatus consisting of a flattened 

 comb-like fascicle of horny setae, which opens outwards or closes down on 

 the retracted animalcule in the same manner as the single valve-like 

 structure in T. valvata; the body projecting, when extended, for nearly 

 or quite one-half its length beyond the aperture of the lorica ; peristome 

 expanding, revolute ; parenchyma frequently enclosing chlorophyll-granules. 

 Length of lorica 1-200" to 1-150". Hab. — Salt and fresh water. 



* ' Infusoires de la Belgique,' 1864. 



