\ 1 4 Systematic guide to the genera and species of Rhizocephala, with anatomical diagnoses. 



H. Hans. Host, Charybdis {Goniohellenus) ornata (M. Edw.), from Suez Canal 5 fathoms 

 (Crossland). 



Remarks. I think it probable that Kossmann's species Sacculina hians parasitic on 

 Thalamita sp. from the Philippine Islands belongs here. 



Three specimens were sent to me by Mr. Crossland from the Eed Sea, two of them 

 being fixed on the same host. 



Although the structure is so similar to that of Sacculina, I am bound to give generic 

 value to a distinct difference in the disposition of the mesentery. 



I was unable to determine the position of the nervous ganglion. 



Genus Lernaeodiscus (Mùller [6]). 



(See Piate 7 figs. 31, 33, 34.) 



Diagno sis. External body of adult yellow. 



Roots yellow, widely distributed and ramifying, without lagenae. 



Mantle and visceral mass muscular, mantle expanded laterally into well-marked lappets 

 (Piate 7 fig. 31). 



Mantle opening situated posteriorly and mesially relatively to host (Piate 7 fig. 33). 



Mesentery very broad and long, running in an hinge round an immense dorsal curva- 

 ture, long axis in same direction as long axis of host (Piate 7 figs. 33 and 34). 



Body compressed antero-posteriorly, dorsal surface being mach elongated and curved. 



King of attachment pierces middle of mesentery, at angle of dorsal curvature. 



Colleteric glands paired and branched. 



Testes paired, showing degenerative signs. 



Genital openings of morphologically left side situated on anterior hinge of mesentery, 

 those of right side on posterior hinge (Piate 7 figs. 33 and 34). 



Nauplius with somewhat elongated and curved frontal horns. 



Endoparasitic development unknown. 



Larvai males not observed. 



Parasitic on symmetrical Decapoda Anomura. 



L. porcellanae (Muller [6]). Host, Porcellana sp. from Brazil. Visceral mass purplish; 

 lappets of mantle very conspicuous and indented. 



L. galatheae. Hosts, Galathea dispersa at Naples, Galathea intermedia from Norway. 

 Visceral mass yellow ; lappets of mantle inconspicuous and irregular. Anterior hinge of mesen- 

 tery not very wide. 



L. strigosae. Host, Galathea strigosa from Naples. Visceral mass yellow; lappets of 

 mantle inconspicuous. Anterior hinge of mesentery very wide. Much larger than L. galatheae. 



