i8 



Jaws of medium strength, strongly curved ; tips long, slender, and sharp. Anterior teeth 

 with very broad bases, closely set; posterior teeth long, not very sharp, divergent distally. 



Vestibular ridge with sharp, fairly regular, projections, terminating externally in a strong 

 process. Corona ciliata long, extending between the eyes anteriorly, and posteriorly covering 

 from one-third to one-half the distance between head and ganglion. Formulae: — • 



It is almost impossible to separate pulchra from enflata by the use of a dissecting lens 

 alone, in many cases of spirit specimens; but microscopic examination distinguishes them 

 satisfactorily. The main points of difference are that in pulchra tUere is a coUarette, and 

 consequentl)- little neck-constriction between head and trunk; the body is slenderer; the fins 

 longer, broader, and closer together; the corona longer; than in enflata. In hcxaptera, which 

 is also of the same general form, there is again little neck, although no collarette is present; 

 bilt pulchra differs from it just as it does from eujïata in the fins and corona, and of course 

 markedly in the number of teeth. 



8. Sagitta regular is Ai da. 



T. AlDA. Op. cit., p. 17. 



L. DoNX.vsTER. Op. cit., p. 211. 



Characters. Head very small ; when contracted, not thickcr than the body immediately 

 behind it. Hody firm; of about the same thickness from the abdominal ganglion \.o the vesiculae 

 seminales; it tapers forwards from the ganglion, bul the development of the collarette at first 

 sight makes it appear of similar thickness anteriorly. A collarette extends from the anterior 

 end of the anterior fins, wider and much longer than in neglecta. Longitudinal muscles broad 

 and stout. Tail 28 to 40 per cent. of the total length. 



Anterior fins narrower and shorter than in tieglecia^ beginning slightly behind the 

 abdominal ganglion. Posterior fins narrower than in neglecta, much more on the tail than on 



