102 JOURNAL OF THE [October, 



by the late Professor H. James-Clark, who connected them in an 

 intimate manner with the microscopic structure of the sponges. 

 They have been studied by Stein, by Saville Kent, and by 

 Butschli in Europe, but in this country, the land in which they 

 were first found and in whose fresh and salt waters they are in 

 profusion, microscopists have almost entirely neglected them ; 

 yet they are worthy of every attention. The explanation of this 

 apparent neglect seems to lie in the small size of the infusorians, 

 and in the consequent demand for high-power objectives in their 

 study. 



The twigs and other objects in the water from the Morris and 

 Essex Canal sent me by my correspondent, were adorned with 

 a great number, indeed with hundreds, of a species of Silpingoeca 

 so nearly resembling James-Clark's Salpingceca gracilis that I had 

 no hesitation in identifying it as that form. But almost at once 

 there entered two facts which gave me pause. First, the animal- 

 cule had a habit which has not thus far been recorded with 

 Salpingceca gracilis nor with any other member of the class; or 

 perhaps I should express it as a modification of a habit common 

 to all, but a modification until now not recorded and presumably 

 not observed. And second, the water, when allowed to evapo- 

 rate in a watch glass, deposited crystals of common salt ; it 

 was brackish water, but without this accidental occurrence I 

 should have called it sweet, although 1 was surprised to find many 

 apparently salt-water Infusoria in it, and was at a loss to ex- 

 plain their presence. This adds another element of interest to 

 the Salpingceca which, although undoubtedly Salpingceca graci- 

 lis, has been modified in habit, presumably by the condition of 

 the water, without a corresponding change in the form of body 

 or of lorica. It has assumed another and more complex con- 

 dition, and seems to be in a transition stage between a salt-water 

 variety of Salpingceca gracilis and a distinct species. The addition 

 of a pedicle to each lorica, each of which except the founder 

 of the colony is now sessile, would force it into a new species. 



The common and abundant form of the Salpingceca gracilis is 

 that shown in Plate 36, Fig. i. It is a solitary animal, rarely 

 being found in near proximity with its fellows of the same species. 

 It may often be seen scattered singly along a thread of alga or 

 of some similar object in fresh water, but it is usually averse to 



