CURIOUS INSTANCES OF PARASITISM IN THE TOAD. 101 



M. Girard. It is also stated that "larvaB of this species have been 

 discovered in the head of a toad, near Maurenne ;" and also, in another 

 instance, near Paris. From these observations it appears that the 

 instances of dipterous parasitism in tbe nasal chambers of toads, 

 as recently witnessed by Dr. McMunn, and by myself some forty years 

 back, are perfectly genuine. 



NOTES ON MAEINE INFUSOKIA. 



BY W. SAVILLE KENT, F.L.S., F.R.M.S., ETC. 



( Continued from page 76.) 



4. — Zoothamnium altemans, C. and L., (Plate IV., Fig. 5.) — This very 

 beautiful type, identical with the Zoothamnium plumosum of Dr. Sfcrethill 

 Wright, tbe Z. spirale of P. H. Gosse, (" Tenby," Plate IV., Fig. b,) and, 

 possibly, the Zoothamnium niveum of C. G. Ehrenberg, (in which case 

 this last-named specific title must take precedence of the others,) was 

 obtained in considerable abundance attached to Sertularia and other 

 Hydroid Zoophytes brought up with the dredge, from various depths. 

 Some of these colonies were remarkable for their size and luxuriance of 

 growth, those obtained from deeper water, fifty fathom3, being most 

 notable in this respect. Compared with the more familiar fresh-water 

 species, Zoothamnium arbuxcula, (sometimes found in sea-waier,) Z. altemans 

 may be immediately distinguished by the mode in which the secondary 

 branches are disposed with relation to the main or axial stem of the 

 compound colony. In the present instance, these secondary branches 

 are given off alternately, sometimes from opposite sides, and sometimes 

 in a spiral manner, producing, in this latter instance, an exceedingly 

 elegant, tall, plumose colonial stock, or " Zoodendrium," which may be 

 indefinitely prolonged. Not unfrequently, and more especially in 

 examples obtained near the shore line, the height of the entire colony 

 does not much exceed the breadth, and, the branches originating at 

 regular intervals on opposite sides of the main stem, the zoodendrium, 

 as a whole, presents a flabelliform or espalier-like contour. In Zootham- 

 nium arbuscula, on the other hand, all the secondary branches diverge 

 radially or close to one another from the apex or distal termination of the 

 main, or axial stem, which latter, being once produced, does not 

 increase in length. 



5. — Zoothamnium dichotomum, St. W., (Plate IV., Fig. 6.) — One or two 

 colonies of a type that, so far as it is possible to predicate, appears to be 

 identical with the form very briefly described in " Pritchard's Infusoria" 

 under the above title, were obtained from the lower depth of fifty 

 fathoms. The zoodendrium, in this instance, is built up by the more 

 or less regular dichotomous division of a somewhat slender primary, or 

 axial stem, the ultimate divisions, or pedicles, which support the 

 associated zooids being of considerable length. In no other species of 



