67 



the author means the rostrum, hut this ohservation is not just, for the attachment certainly 

 takes place by a frontal thread; moreover, I suppose that the animals Salensky took for 

 males were in fact somewhat younger females without marsui)ium, founding this suggestion 

 partly on liis (otherwise bad) description of the host »Ampliitoe sp.«, — according to Delia 

 Valle : Microdcutopus ijriiUotaJpa Costa,, — in which he does not say a word about the very 

 gi'eat difference in the »hand« of the first paii- of trunk-legs between the two sexes, partly 

 on the fact that I have never found a SplKeronella on any adult male ; whether some of the 

 not full-grown specimens on which I found typical niarsupium-parasites, were young males, 

 I cannot tell, but I doubt it. The twenty-four of the species parasitic on Amphipoda I 

 have found exclusively in marsupia, and though, in not full-grown animals, I may not 

 unfrequently have overlooked larvae, pupae or very diminutive females, in any case I cannot 

 have overlooked many females with ovisacs. Only in the following four species of Amphi- 

 poda : Metopa Bruzelii (Goes), Argissa tyinca'Bo^ck, Proiomedeia fasciata Kr. and Ampelisca 

 tenuicornis Lilljbg. , have I found i)ara sites in specimens without or with half-developed 

 marsupium. In a specimen with scarcely half-developed marsupium of Metopa Bruzelii, two 

 larvae were found, and in a still younger one without marsupium, a single larva. In two 

 young females without marsupium of Argissa typica appeared respectively one pupa and a 

 tiny female of Splicer. Argissce. In a young specimen of Protomedeia fasciata Kr. , from 

 Greenland, were found a not half-grown female and a male of Sphm-. Bovnieri. Splurr. 

 Jongipes I found in nine specimens oi Ampelisca temricorvis: two of these only were females 

 with fully developed marsupium, the third was a young female with half-developed marsupium, 

 •wliich contained a not half-grown female of the parasite; the six remaining specimens were 

 young, without marsupium, and on each of the five of these I found a single female between 

 not half-grown and very small, — in one case even recently hatched; in the sixth spe- 

 cimen there were only two loose larvae. The result hereof is, that in Ampliipoda I have 

 not found a single adult female in a specimen without entirely developed marsupium, and 

 never ovisacs except in marsupia. It is probable that larv;* not unfi-equently fix themselves 

 to immature females, beginning their development there, and thus entailing the necessity 

 that lai'vae as well as young females, and raiely males, remain on the host, while it passes 

 thi'ough its last moultings; however, as said above, not a single observation has been made 

 of ovisacs being found in females not fully developed, wliich by the by, seems natural 

 enough, as they would certainly be washed away, if they were laid. However, I cannot 

 prove that most specimens are infested before the marsupium is fully developed. No doubt, 

 the larvae seek either perfectly mature females — and at least rather often those whose 

 marsupium is already infested by at least one (half-grown or quite adult) female and a male 

 — , or such younger specimens as are so far advanced, that they will have got their 

 marsupium before, or at the time when the females that have developed themselves out of 

 some of them, are ready to begin laying eggs. Whether the larvae of species that live in 



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