554 Chas. W. Hargitt 



(|uite lackinc: in tliose boru severa! days later. The colony conti- 

 nued to live, however, and medusae were liberated during an entire 

 week, at the end of which time the hydroids were killed and pre- 

 served for subsequent study of morpholoc:ical details here-in-after 

 described. Most of the material was fixed in alcoholie-corrosive 

 Solutions, and in 10^ Solutions of formalin in sea-water. 



It may be remarked, incidentally, that of the preserved mate- 

 rial some was worked up soon after preparation. and other portions 

 after my return several months later, and with an experience simi- 

 lar to that which I have elsewhere mentioued, namely, that better 

 results were obtained from the newly prepared material than from 

 that long preserved. This I believe may be regarded as a general 

 rule having few exceptions so far as coelenterates are coneerned. 

 Sections were in almost all cases stained by means of Heidenhain's 

 iron-haematoxylin , followed in some cases by Bordeaux-red , with 

 excellent results. 



Systematic. 



The genus Pachycordyle was instituted for a hydroid found by 

 Weismann at Naples, and described by him in his monograph i. It 

 is unnecessary to cite in detail his description of the hydroid except 

 on certain points involved in comparisons. 



As I have noted above, the general features of the present 

 hydroid have much in common with that described by "Weismann. 

 The one feature in particular which would seem to sharply distin- 

 guish the two is the fact that Weismann's species is recorded as 

 having only sessile gonophores while in the present case, as already 

 cited, the gonophore is a free medusa, however, a short-lived one. 



It should be noticed in this connection that Weismann's speci- 

 mens were all male , while strangely enough in the present case I 

 was only able to obtain female colonies. Whether this circumstance 

 of itself affords room for doubt as to the specific difference of the 

 two may be open to some question , of course , tho so far as my 

 observations have gone, as a rule where the medusa is free in one 

 sex of a given species it is almost invariably free in both. I have 

 elsewhere shown^ that occasionally specimens of Pennaria tiarelia 

 are found in which many of the female medusae discharge their 



* Die Entstehung der Sexnalzelleu bei den Hydromedusen. Jena 1883 

 pag. 87. 



2 Amer. Natural. Vol. 34 1900 pag. 391. 



