138 PROF. W. M. SMALLWOOB OX HYDROIDS [Jan. 18, 



portion moderately elongated ; base flattened ; mantle beaded 

 immediately over the tail. 



" Color bright blue above, variously lined and streaked with 

 light yellow ; on the dorsal surface the yellow markings are 

 disposed in longitudinal wavy or nearly straight lines, one or more 

 specially prominent lines along the dorso-lateral border. Sides of 

 animal irregularly reticulated or angulated with yellow markings; 

 under surface pale blue, bordered with faint yellow. Rhinophores 

 deep incligo or black, the rhinophoral aperture bordered with 

 yellow ; gills 12 or 13, black, bordered with yellow, and carrying 

 blue cilia ; under surface of head blue, with yellow spots. 



" Length, when expanded, three and a half inches. Three 

 specimens, dredged in about ten fathoms on the north side of 

 Harrington Sound." 



The few observations by Heilprin on the internal anatomy do 

 not serve to distinguish this species from the other Chromodoridse 

 and so are omitted. He gives two rather generalized figures with 

 but little accurate detail. 



Other than the above, no description of this species has been 

 made, so far as I have been able to determine. Bergh (92) 

 questions whether C. zebra is a distinct species from C. vittafranca, 

 but this can not be settled until the anatomy has been thoroughly 

 worked out ; this will be done in a separate paper. The following 

 observations on the external morphology add a number of facts 

 to Heilprin's description. 



Over fifty specimens were available for observation during the 

 month, which gave ample opportunity to note a number of 

 variations. The length of the body from the anterior tip of the 

 mantle to the posterior end of the foot is 16 cm. This is the 

 average length of the animals as they were crawling around in 

 the aquaria. The body is much elongated and linear ; it is 

 thickest just anterior to the branchial plumes, becoming slightly 

 depressed anteriorly. The mantle is rounded at each end and a 

 little wider than the foot ; it is slightly broader in its anterior 

 than in its posterior portion, and projects beyond the end of the 

 tentacles. The foot is uniformly narrow and linear ; it tapers off 

 to a point posteriorly, but its anterior end is squarish with 

 rounded corners. 



The ground-colour of the animal is blue. The foot is pale blue, 

 but the intensity of the colour varies with different individuals. 

 The margin and posterior tip are almost free from this ground- 

 colour. The bottom of the foot is not modified by any other 

 colour. The protrusible pharynx is likewise deeply coloured with 

 a similar unmodified blue. This ground-colour of blue is not as 

 conspicuous on the rest of the body, where there is a series of 

 irregular streaks and a mottled effect produced by colours which 

 range from a dark olive to orange. These markings are by no means 

 the same in all individuals. In fact, of two dozen animals 

 collected from the same spot at the same time, no two specimens 

 were found to be alike. The dorsal margin of the foot is free 



