70 



now SplKProfidla 3Irtop(r\ but never bntli forms in the s^ame sjien'men. In a laige material 

 of the same host from another Greenlandish locality appeared a number of specimens of the 

 former, not one of the last-mentioned paiasites. On specimens of Hippoli/te Guimarrlii 

 M.-Edw. trom the Kaia Sea appeared now Choniodoma miraJiilf, now Ch. Hansen ii , and 

 the latter species was also found in Hijip- poJaris (Pab.) trom the same sea. In Danish 

 specimens oi Ampelisca /r-ww/cor^/.s- Lilljbg'. I have foinu] SjiJufronilla Jonyiins; whereas Giard 

 and Bonnier have found in sjiecimens of the same species from le Croisie (Brittany) the 

 very deviating Spliar. mhroaphala. Danish specimens of Prvtomeclcia fasciafa Kr. were 

 infested with SpJiar. Giardii, and Greenlandish specimens witli the closely lelated species 

 Sjjhfpr. Bonnieri. On a specimen of Iphinoi- trispinosa (Goods.) from Messina Homocoscclis 

 meditprranea was found in the bianchial cavity and Sphcrrovcllu marginatit in the niarsupium. 

 In Norwegian sjiecimens oi IJrytJnvjhs scrrafiis G. O.Surs and Eiptlirops ahysmrum G. O Sars 

 we not unfrecpiently find a species of Whishlioit in the marsupium, and one or several 

 specimens of Aspidoecia Normmii on the outside of the body of the same species. In one 

 specimen I found two specimens of the latter species on the outside of the body, an adult 

 and a young female of Mi/sidion ahyssornm , and a young female of Mys. commune in the 

 marsupium, wliich makes three species of parasites on one animal. 



e. Number of Species of Hosts of the different Parasites. 



The answer to this question presupposes the answer to another, namely that of the 

 limitation of the parasitic species, and as this latter question is not treated in detail till 

 later on in a separate chapter, I will content myself with mentioning the results of tliis 

 examination, using them in answering the question indicated by the heading. 



Twenty-nine of my species, as a matter of fact, are only found each on one particular 

 species. Of the remaining fourteen species eight (belonging to the group oiSjiliirr. Lmclrmiii) are 

 also limited each to one particular species; however, it may pei haps be questioned whether these 

 eight species can really be maintained as such, or must be regarded as chance varieties of a 

 single species (see later on). The remaining six species must be mentioned each separately. 

 Choniostoma Hansenii has been ascertained in two species: Hiji2MJyfe GaimardiiM.-EA\Y.RnA 

 Hippolyte polaris (Sab.). Of SpharoneJla insignia indeed I have only had a small material which 

 was taken on DiastyUs cornufa Boeck and Biastylin lari,^ Norm. ; howevei', the diflerence between 

 the parasites of the two species was so slight, that my experiences from other species led 

 me to consider them as belonging to one species. The species found by Giard and Bonnier 

 on Ampelisca tenuicornis Lilljbg. from le Croisie, which they have described under the name 

 of Spluer. microcephala , as far as I can see, is identical with the species described by me 

 in tliis work under the same name, and this is taken on Ampelisca typica Sp. Bate in Danish 

 waters. Sphceronella paradoxa I have found on Bathyporeia norvegica G. 0. Sars, Bathyporeia 

 pelagica Sp. Bate and B. Eobertsonii Sp. Bate, and even if it were proved that the two 



