182 THE ZOOLOGIST. 
Order PULMONOBRANCHIATA. 
Fam. LimynxID2&. 
Planorbis lineatus.—The Bootham ‘ Observer’ states that this © 
used to be observed in the Hobmoor ponds. The same authority 
says that in 1855 it was found in the ponds on Tillmire, and four 
years later in the direction of Osbaldwick, but I have met with it 
nowhere except at Askham, where in certain of the ponds it 
positively teems, though in others it is not found. Unlike the 
following species, which generally lives among decaying leaves 
in very stagnant ponds, this seems to prefer clearer and shallower 
pools where grass is growing. 
Planorbis nitidus.—Rather sparingly distributed in the York 
district. I have found it, but not commonly, in the Foss and 
in one pond at Hobmoor. A pond near Rawcliffe Lodge (H.) 
Abounds in a pond beyond the first toll-bar on the Wiggington 
road and in some of the Askham ponds (H.) 
Planorbis nautileus.—Found abundantly in some ponds at 
Askhain Bog and Hobmoor, rarely in the Foss, and very probably 
in other places, but its small size renders it difficult of discovery. 
Rare in the Ouse (R.) Several ponds near Clifton, but specimens 
from here are only slightly “crested’”’ compared with those from 
Askham (H.) The caddis-worm is very fond of sticking the shells 
of this species to its case, their roughness doubtless giving a 
secure hold. I have cases with one hundred or more sticking 
to them. 
Planorbis albus.—Sparingly distributed. I have met with it 
pretty commonly in the Foss; also in some of the ponds on 
Strensall Common, at Hobmoor, and Askham. Near Osbaldwick 
(‘ Observer,’ 1859). Pond on Clifton Jugs in profusion (H.) 
Holgate Brick Ponds (H.) 
Planorbis spirorbis.—General and abundant, particularly in 
the many small ponds in the corners of fields near the Bookham 
Junction signal-box. Also Askham and other places. It teems 
on the Bog now (H.) 
Planorbis vortec.—In great numbers in a ditch on Clifton 
Jugs, a pond beside the Foss, and a few other places, but by no 
means common or widely distributed. Mr. Hey has never found 
this, and doubts whether I am not mistaken. 
