170 THE MEDUSAE. 



it may seem in the present specimens, is not a constant nor an important 

 character. 



Both the specimens have eight large radial tentacles, and between 

 every two tentacles from one to three triangular bulbs (PI. 38, fig. 2) ; but 

 there is no evidence that any of the latter are developing into tentacles. 

 Both tentacles and bulbs bear excretory papillae (PL 38, fig. £, p. ex) on 

 the oral side of their bases, such as have been described by Browne (: OS*"). 

 There are from three to five otocysts between every two radial tentacles. 



The manubrium is very short, the mouth surrounded by eight pointed 

 lips (PI. 38, fig. i). 



The specimens were entirely colorless in life. 



These Medusae would readily be referred to 0. polt/nema as immature 

 stages were it not for the fact that the gonads and ova are far ad- 

 vanced. As it is, it seems to me at least open to question whether the 

 rudimentary marginal swellings between the radial tentacles would in 

 the Acapulco form grow into tentacles ; but it is impossible to answer 

 this without more material. Unfortunately it is exactly this information 

 which is requisite to determine their specific identity. 



Aequoridae Eschscholtz, 1829. 



sens. em. Maas ('93, : 05). 



Leptomedusae with numerous radial canals (more than eight) ; with 

 numerous closed otocysts ; tentacles with basal bulbs and excretory papillae. 



There is no question but what Haeckel ('79) went much too far in split- 

 ting up this family, since some at least of his genera were undoubtedly 

 based on conditions of the stomach which were either accidental or 

 the result of contraction. On the other hand, Claus ('80) has probably 

 gone too far the other way in uniting all aequorids in the single genus 

 Aequorea. Browne (:04, : 05'') and Maas (:05), in recent publications, dis- 

 tinguish two genera, Aequorea with well-developed stomach and a mouth 

 capable of being closed, and Mesonema, in which the gastric wall is rudi- 

 mentary, and the mouth not capable of being closed but of almost as great 

 diameter as the stomach ; but although there are probably two (or even 

 more) genera of Aequoridae, this separation, based on the condition of the 

 mouth, seems to me no real advance over the previous attempts. In the 

 first place, I doubt whether the non-closable mouth actually occurs in any 



