2I() 



ol" a large luinihor ol" ;mimals in llic liopics would slill he very iiseliil." 

 (Op. c-il. p. ;ir)5). 



Willi Iho latler senU'iice I most heartily agree, hut otherwise 1 iiuist 

 (k'cidodly object lo llie slaltiiu'iil that in the tiopical seas the animals arc 

 conliiuiously hieeding al least as regaids the lu'hiiioderms. and I caii- 

 nol hut wonder how Semper came to the above result. It is true Ihal I 

 have made only lew observations, as regards this point, during my slay at 

 the Philip|)incs; but al any rate I found that the large Si/iuipta Ueselii had 

 no ripe sexual products in February March al Zaudjoanga. And it is 

 certainly not to be assumed that the animals behave otherwise al tiie 

 IMiilippines than elsewhere in the tropics, as regards theii Ijreeding. My 

 observations decidedly prove that a I least several of the littoral Kchino- 

 derms do not breed continuously. Thus e. g. I never found Ihe opportunity 

 for studying the development of Dindvnw, until I came lo Tobago, li. \V. I. 

 and there found I). anlilUimm to have ripe sexual products in the end of 

 March; and when, about a week latei- on, I wanted to start a new larval 

 culture it was impossible to liiid one specimen containing ripe sexual pro- 

 ducts, all were ipiite em])ty. A similar experience 1 had with Echinomelrn 

 van lirunli, Brissus obesus, Slichopus Kefersteinii, and in several cases I 

 had, to my great annoyance, to give u|) any hope of obtaining a larval 

 culture, because the breeding season did not coincide with my slay (e. g. 

 Echinoneus). — On the other hantl, 1 have some observations tending 

 to show that in the tropical seas Echinodernis (some foiius, at least) have 

 more than one breeding season in the year. Hut for |)roving this defini- 

 tely observations must be continued through a longer ])eriod, a stay of a 

 few^ months being, of course, insufficient for such a task. 



1 would recall here that I have been able to prove (Die Kchinuiden d. 

 Deutschen Siidpolar-Expedition. p. 71)') that the Antarctic Slerechinus 

 Neumaijeri breeds at least from .lune to April, which fact is doubtless due 

 lo the very uniform temperature reigning in the .\nlarclic Sea throughout 

 the year. This case then confirms Orion's statement that "where bio- 

 logical conditions do not vary nuich, marine animals will breed continu- 

 ously." I would only object lo making this a general rule; this it is cer- 

 tainly not, especially not in the tropics. 



') Deutsilic Siiil|)olar-I-;xi)C(litioii. Zoologio. III. 191)'.). 



