18 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxvi. 



to determine whether the castration so general among these females 

 is due to a parasite, Microsporidian or Bacterian, or simply to hun- 

 ger. Neither do the S. longicm^pus which accompany them possess 

 their maximum size ; the males are largely in excess, but the eggs of 

 the female are altogether normal. 



One frequently finds some anomalies of the same sort in S. hrooksi 

 Coutiere, in which the eggs give rise also to mysis as in S. pectiniger. 

 The eggs may be reduced to two or three; they are then very small 

 and of a chalky aspect, and at the same time the size of the female 

 is very much reduced. S. rathhunm is known to me up to the present 

 time only by some sterile females, very small, in which the pleura are 

 extremely spinous as in the male. 



These species appear, then, to be sometimes found in very precari- 

 ous conditions, from the point of view of their perpetuation, and 

 the study of these conditions would probably be most interesting; 

 their abundance in the collections accords well with what Herrick 

 says Avhen he speaks of the constant fusillade which one hears on the 

 reefs of the Bahamas from the movements of the Alpheids, and it 

 seems to me that they would lend themselves to constant observation 

 in an aquarium in such a manner as to make possible some "" pure 

 cultures " of a determined species. 



After an examination of the facts, it is difficult to avoid the temp- 

 tation to draw from them some hypothetical conclusions. When one 

 investigates the distribution of the Synalpheids known at the present 

 time, the most striking fact is the existence of forms almost identical 

 in regions so remote as the Red Sea and California or Florida. Now, 

 these are very sedentary animals, which are almost never seen to 

 swim, but live in couples in sponges or madrepores ; their larvae, to be 

 sure, could be disseminated by the currents, but the possible extent of 

 that dissemination should not be overestimated, and when two spe- 

 cies are separated by both the Pacific and the Indian oceans, they are 

 certainly isolated in the most rigorous fashion. I can not repeat too 

 often that the Indian S. paidsoni and the Californian S. paulson- 

 o'ides, S. tnushaenis and S. lockingto/ii, /S. acanthitelscmis and S. 

 apioceros, S. nilandensis and S. hemphilli., etc., might very well, with- 

 out indication of locality, be considered as simply " races," and there 

 is the inevitable inference that former conditions under which the 

 antecedent species lived permitted a very vast distribution. Nothing 

 shows that these species still exist, but at all events they have 

 changed, since the forms which represent them in different localities 

 are no longer exactly comparable. There is, as an exception, only 

 the single species S. latastei., the specimens of which from Chile I can 

 not differentiate from another — a single one, it is true — from Austra- 

 lia. This exception, when critically examined, only goes to strengthen 



