122 Systematic guide to the genera and species of Rhizocephala, with anatomial diagnoses. 



The nervous ganglion (fig. 1 2 gn) is large and well developed, the nuclei staining rather 

 conspicuously as in Sylon. 



The two bodies which I interpret as possibly complemental males have been minutely 

 considered in Chapter 2 pp. 31, 32. Figs. 14, 18 and 19 on Piate 13 refer to them. 



Genus Apeltes (LlLLJEBORG [4]). 



Lilljeborg founds this genus for a single specimen taken on Eupagurus bernhardus 

 from Bohuslàn. It resembles Clistosaccus in its large discoidal ring of attachment and in the 

 apparent possession of a single testis which has however two vasa deferentia. The mantle 

 moreover has an opening anteriorly, and also according to the description a posterior opening. 



The nature and position of this parasite can hardly be correctly adjudged at present. 



Genus Thompsonia (Kossmann [11]). 



Kossmann has formed this genus for a parasite found by Semper attached to the leg 

 of a Melia tesselata from Aibukil, Palaos. The only characters given are the great length 

 of the peduncle of attachment and the presence in the mantle cavity of larvae in the Cypris 

 stage. The lattei- character is very interesting and is confirmed by Semper himself who gives 

 a figure of the Cypris. 



Further investigation of this genus is much needed. 



Genus Tliylacoplethlis (Coutière [26]). 



This is an highly interesting genus found gregariously, about an hundred on each host, 

 upon specimens of Alpheus from the Australasian seas. 



The root system is described as not extending far into the tissues of the hosts; but 

 since no mention is made either of a mesentery or of a testis in Coutière's description it is 

 impossible to judge of the afnnities of this genus. 



