H(] Systematic guide to the genera and spccies of Rhizocephala, with anatomical diagnoses. 



Kemarks. Among ali the various names that have been given only two represent truc 

 species to a certainty, namely P. paguri and P. sulcatus. It is interesting to note that botti 

 these species have an enormous distribution, from the Arctic circle to Brazil. None are known 

 from great depths. 



The anatomy and the biology of the Neapolitan race of P. curvatus has been the 

 subject of so many of the observations in this book that I need not go further into it here. 



Genus Parthenopea (Kossmann [12]). 



Diagnosis. External body of adult red. 



Roots green, widely distribnted and branching, without lagenae. 



Mantle and visceral mass muscular. 



Mantle-opening situated laterally, relatively to host. 



Mesentery rather thick, short, running in the actual shortest axis of the body and 



vertical to long axis of host. 

 Body roughly spherical, slightly compressed antero-posteriorly. 

 Ring of attachment situated at posterior end of mesentery. 

 Colleteric glands paired, slightly branched. 

 Testes paired, showing slight partial degeneration. 

 Nauplius without frontal horns (Kossmann). 

 Endoparasitic development unknown. 

 Larvai males not observed. 

 Parasitic on Callianassa (and Gebia). Solitary. 



P. subterranea (Kossmann [12]). Hosts, Callianassa subterranea and according to Giard (20) 

 Gebia stellata, Naples. Since this is the only species, the diagnosis for the genus gives the 

 characters of the species. 



Remarks. Dr. Lo Bianco informs me that this parasite was formerly exceedingly 

 common at Naples, but that it is now becoming gradually extinct. He has however been able 

 to furnish me with several specimens. 



Genus SaCClllina (Thompson [1]). 



Diagnosis. External body of adult yellow when Nauplius larvae in brood-pouch are immature, 



purplish when they are mature. 

 Roots yellow, very widely distributed even into the appendages and highly branching, 



with lagenae. (For lagenae see Note on p. 113.) 

 Mantle and visceral mass muscular. 

 Mantle-opening situated posteriorly, relatively to host. 



