297 



from the pylidium. Dr. Mcintosh does not say whether he 

 ■would accept this view of the matter or not. It woukl be 

 impossible for us here to even give a summary of the con- 

 tents of Dr. Mcintosh's wonderful paper without entering 

 into a vast number of controversial topics as to anatomical 

 details in these worms. One little thing we can allude to is 

 a very curious ciliated parasite which drills the body of 

 Borlasia through and through, and is very like an Opalina ; 

 but Dr. Mcintosh does not describe contractile vesicles, nor 

 nucleus in it. The interesting point is the segmentation of this 

 ciliated creature, recalling the Opalina prolifera of Claparede, 

 and adding another to the list of segmented infusors, and 

 tending to upset the view that segmentation can be held to 

 furnish any criterion of genetic affinity in groups of organisms. 

 Keferstein has observed a similar parasite in the planarian 

 Leptoplana. Dr. Mcintosh draws a wide line between the 

 group of which Ommatoplea is tlie centre (Enopla), and that 

 of which Eorh\>ia is (Anopla). With the exception of 

 Cephalothrisc and another all the British Nemerteans can be 

 grouped round these two types. We congratulate Dr. 

 Mcintosh on having secured Mr. Ford to execute his plates. 

 We would simply say that they are the very best illustra- 

 tions of microscopic structure that we have seen drawn by an 

 English artist, and equal to the best of German work. We 

 hope j\lr. Ford will find time to undertake more microscopic 

 plates : we must not, at the same time, forget that the author 

 made the original drawings himself, the excellence or rough- 

 ness of which makes all the difiference in the engraver's 

 work. 



Zoologists and microscopists may point to Dr. McIntosh''s 

 elaborate paper with much pride as a specimen of British 

 scientific research, which Ave heartily wish did not stand so 

 niuch alone in its excellence. 



If" Dr. Mcintosh had given a brief resume of the points 

 which he chiefiy desired to establish at the end of his paper, 

 it would have been a convenience. 



Protohydra Leuckarti, a marine stock-form of the Calen- 

 terata. By Dr. Eichard Grcef, of Bonn. 2 plates. Koll. 

 V. Sieb. Zeitschrift. 1st part, 18T0. The interesting form 

 here described by Dr. Greef was observed by him in 1868 at 

 Ostend in a quantity of diatom-scum and alga?, Avhich he 

 brought home for observation from the oyster park. It is 

 remarkable as presenting very much the histological charac- 

 ters of the common fresh-water hydra, but its gross structure 

 is far simpler, for it has no tentacles Avhatever. Moreover, it 

 reproduces bv a process of transverse fission, very much like 



