190 



pentagona not being the same species as A. exigua as it is generally thought 

 to be. It is also on zoogeographical grounds very probable that the spec- 

 imens from Cape are not the same species as the Australian form. Un- 

 fortunately, Ludwig does not state from which locality his specimens 

 came. But, in any case, the fact thus ascertained that the genital pores 

 are on the ventral side in the Australian specimens, on the dorsal side in 

 specimens from some other locality (Cape?) shows that what has hitherto 

 been included under the name of Asterina exigua is not all one and the 

 same species. 



It can hardly be doubted that the ventral situation of the genital pores^) 

 in A. gibhosa and exigua is not a character of greater systematic value 

 ( — the two said species are referred to different genera in Verrill's revi- 

 sion of the Asterininse^) — ), but only an adaptation to their breeding 

 habits, and it seems then legitimate to draw the conclusion that the same 

 habits will be found in other species showing the same position of the 

 genital pores. An examination of the material of Asterina in the collections 

 of the Copenhagen Museum, which contains most of the known species of 

 the genus (s. lat.), shows that, with one single exception, these species 

 have dorsal genital pores, and it may therefore be concluded that pelagic 

 larvae are the rule in the As^erJna-group, direct development exceptional. 

 Only in one case, besides A. gibbosa and exigua, I find ventral genital 

 pores, viz. in a small Asterina from the Uttoral region of Misaki, Japan, 

 which appears to represent a new species; at least it is not identical with 

 any of the species mentioned from Japan by Goto^). It may accordingly 

 be expected that also this species will prove to have a shortened develop- 

 ment. — This species, moreover, is interesting in being selfdividing in its 

 younger age, the only other case of selfdivision hitherto known among 

 the Asterinidse being Asterina Wega Perr. While the species is normally 

 5-rayed, the specimens arising through divisions are often 6- or 7-rayed. 

 Only very small 6— 7-rayed specimens were found. (Possibly this self- 

 dividing form is not really the same species as that with the ventral 

 genital pores). 



1) It is interesting to notice that also tiie male specimens of A. exigua have ventral genital 

 openings; Ludwig does not state, whether this is likewise the case in A. gibbosa, but it 

 may seem probable from analogy with A. exigua that it is so. 



2) A. E. Verrill. Revision of the genera of starfishes of the subfamily Asterininae. Amer 

 Journ. Science. 4. Ser. XXXV. 1913. p. 477. 



») Seitaro Goto. A descriptive Monograph of Japanese Asteroidea. I. Journ Coll 

 Science Tokyo. Vol. XXIX. 1914. 



