16 
In 1892 I published an essay: »Rhizorhina Ampelisce n. gen. n. sp. En ny til 
Herpyllobiide n. fam. horende Copepod, snyltende paa Ampelisca levigata Lilljeb. (Entomol. 
Meddelelser, 3. B. 5. Hefte p. 207—834, Tab. III), which in the first place contains a detailed 
description of the above-mentioned new and very curious form, in the second place makes 
an important contribution to the knowledge about Herpyllobius Stp. and Ltk.; finally the 

new family Herpyllobiide is established, and the genera — seven in all — which can with 
more or less certainty be referred to it, are grouped together. Two of these genera, 
Trophoniphila MW’ Intosh and Oestrella M’ Intosh, are described so defectively that we prefer 
not to consider them in this place. The female of the other five genera has a globular or 
oblong body without any vestige of mouth or limbs; posteriorly are two genital apertures, 
each with its ovisac. The front part of the female of Rhizorhina forms a short, slender 
stalk, which pierces the skin of the gill of its host; the inside of this stalk consists of two 
tubes. Just beneath the skin of its host the stalk expands very much, the tubes are consi- 
derably dilated, they separate and ramify irregularly throughout the gill, even entering 
somewhat into the body of the host. In the genera Herpyllobius Stp. and Ltk. and Ewry- 
silenium M. Sars, the stalk, which consists of a single tube, is found on the ventral side of 
the body, pierces the skin of its host and expands inside it like a collar, but this collar is 
surrounded by the root of a large, oblong, foliaceous or irregularly sausage-shaped body, 
which is decidedly homologous with the tubes of the Rhizorhina, and, like these, has the 
function of drawing nourishment from the host to the external, limbless body, whose business 
it is to develop the eggs. In Saccopsis Ley. and Bradophila Ley. Levinsen has indeed found 
the stalk, but no body at the expanded end of it in the body of the host. However, he had 
but slight material of both forms to work with, so I will now state as my personal opinion, 
that a body, or one or two tubes, may have proceeded from the stalk into the body of the 
host; otherwise it would be impossible to understand how the parasites could get their food. 
Moreover, I may mention that, when (in Noy. 1896) I spoke to the author, Inspector 
G. M. R. Levinsen, about the matter, he felt inclined to share my opinion. Giard and Bonnier 
(in their above-mentioned paper) describe a new parasite, Salenskya tuberosa, of which a 
single specimen was found on Ampelisca spinipes Boeck from Croisic. They confess (p. 474) 
that it »présente certainement une tres grande ressemblance avec Rhizorhina ampelisce .... 
et nous avons longtemps hésité a maintenir le genre Salenskya, crée par nous {in the  preli- 
minary note] quelques mois apres la publication du travail de Hansren«. Still they think 
they are justified in maintaining it, »au moins provisoirement«, on the following basis: 
»Au lieu d’étre fixé a son hote par des racines rappelant un peu celles de Succulina, 
ou par un renflement comparable a celui des Herpyllobius, la femelle de Salenskya possede 
un appareil chitineux spécial, qu'on pourrait rapprocher plutot de celui de Saccopsis terebellidis 
figuré par LEVINSEN...... «(p. 475). I have just spoken of Saccopsis, and 1 will now express 
my opinion that if a specimen of Salenskya is found again on Amp. spinipes, and the part 
of the host occupied by the parasite is cut off, this part will contain internal tubes exactly 
