A PUZZLE TO ZOOLOGISTS. 265 



visional, will scarcely be denied. They have not the 

 stable basis which can make future researches the 

 simple extension and application of existing principles. 

 A new method is inevitable ; but we may be years 

 before it is promulgated. An instructive example of 

 our inability to apply the present Method, otherwise 

 than in a provisional way, is afforded by that puzzle 

 to zoologists, the Sagitta hipunctata (Plate V., fig. 1.) 

 Nobody knows where to place it. In aspect it is fish- 

 like ; in some structural peculiarities it is fish-like ; 

 in others "xi> xo molluscan ; in more it is annulose. 

 Siebold classes it Avith mollusca ; Huxley and Krohn, 

 with the annulosa, the former pointing out that " it 

 presents equally strong affinities with the four principal 

 groups — 1. The Nematoid worms; 2, The Annelida ; 

 3. The Lernaean Crustacea ; 4. The Arachnida."'"' 



Place it where we will, the animal is very interest- 

 ing, either when darting about in a glass vase flapping 

 the water with its tail, and fixing itself to the side 

 of the glass (using the vent as a sucker ?), or seen on 

 the microscope stage, where its extraordinary transpa- 

 rency obliges a liberal use of " stops." It is then seen 

 to have a head with a formidable set of hooks (which, 

 however, do not seem to fulfil the office of jaws), and 

 two large eyes. The narrow body is divided into two 

 equal lengths (in my specimens this was so ; in the 

 figures published by Mr Busk and Mr Gosse the an- 

 terior portion is considerably the larger) ; in the upper 

 half lies the straight alimentary canal, terminating in 



* Report of British Association, 1851. Sections, p. 78. 



