22 SIR CHAELES ELIOT. 



larger than the line of the cerata, and the reddish ramifications are clearly visible 

 through the skin. The diverticula within the cerata, on the other hand, are only 

 visible with difficulty, being of the same colour as the integuments as preserved. 

 In structure they are similar to the same organs in N. gigas. 



FIG. 24. Notaeolidia depressaa FIRST LATBBAL TOOTH ; 6 SECOND ; c THIRD ; d FOURTH. 



The reproductive system is not much developed, and the animal, considering 

 its relatively small size, is probably sexually immature. The follicles of the 

 hermaphrodite gland lie among the hepatic branches, but do not form a thick mass 

 above them, as in N. gigas. The anterior genital mass is small and yellow, the 

 spermatotheca of moderate size and roundish, the vas deferens long and much 

 convoluted. 



CRATENIDAE. 



(See Eliot, Jour. Mar. Biol. Assoc., VII. (1906), pp. 363-366.) 



THE division into genera of the forms comprised in Dr. Bergh's family Cratenidae is a 

 matter of great difficulty. Phestilla is distinguished by its dentition among other 

 points, and Hervia by its elongate shape ; but Cuthona, Cuthonella, and Cratena are 

 not easily separated from one another. None of them have any very remarkable 

 characteristics ; they are smallish Solids, neither very long nor very stout, with 

 simple rhinophores, cylindrical cerata. a foot rounded in front or with inconspicuous 

 projections, and teeth of the common horse-shoe shape, bearing a moderate number of 

 denticles (usually less than twelve) on each side of a central cusp. 



In Jeffreys' " British Conchology," Vol. V., Alder divided many of the forms 

 comprised in these genera between Cuthona, having the branchiae close set, and Carolina, 

 having them in rather distant rows, and also having the central cusp of the teeth a 

 little prominent. But the name Cavolina is preoccupied, and the difference between 

 close set and distant rows is one of degree, which may be obscured in preserved 

 specimens. According to Dr. Bergh's definition, the difference between Cuthona A. and 

 H. and Cratena Bergh is very slight. The former has caput latum . . . podarium 

 antice rotundatum, the latter, caput non latum, podarium antice leviter arcuatum. 

 Cuthonella Bergh is more distinct. The foot has pointed corners in front, the 

 jaws bear several series of denticles, the anus is latero-dorsal, and the otocysts 



