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



115 



L. papilio [= Kossmann's [11] Sacculina papilio). Host, Porcellana sp., Philippine Islands. 

 Impossible to diagnose from description, but resembles L. galatheae, and certainly belongs to 

 this genus. 



Remarks. Relying on the position of the mesentery, the lateral expansions of the 

 mantle, and the nature of the host, I have placed all these forms in Muller's genus Lemaeo- 

 discus, but the main features of the anatomy from which the diagnosis of the genus is made, 

 are drawn from a careful study of L. galatheae alone, which is fairly common at Naples. 



Muller in his description of L. porcellanae gives no clue to the exact position of the 

 genital openings on which so much depends. 



Genus TriailglllllS. 



Diagnosis. Resembles Lernaeodiscus, save that the anterior hinge of the mesentery is absent, 

 and the ring of attachment appears to have shifted posteriorly into the middle of 

 the posterior hinge. 



The genital openings have concomitantly shifted, and are situated in an highly asym- 

 metrical position at the anterior edge of the mesentery. 



Mantle opening often situated asymmetrically relatively to long axis of host. 



Parasitic on symmetrical Decapoda Anomura. 



T. munidae. Hosts, Munida bamffica from Norway, shallow water, and Munida tenuimana, 

 about 500 fathoms. 



Diagnosis of species that of genus. 



Remarks. I have only been able to examine macroscopically two specimens, so that 

 I could not observe the nervous system, nor the minute characters of the genital system. 

 The parasite is plainly closely allied to Lernaeo- 

 discus, but, as in the case of Heterosaccus and 



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Sacculina, I must treat the important difference 

 in the mesentery as of generic value. I insert 

 here a diagram to illustrate what I conceive to 

 be the anatomical relations of the different parts 

 of the body. 



The parasite is viewed by transparency 

 from the anterior dorsal face, i. e. the face in 

 Lernaeodiscus which carries the anterior hinge 

 of the mesentery. Consequently we only see 

 the mesentery [rnes) at its free anterior edge 

 here, the rest being on the under surface of 



the visceral mass [vise). The ring of attachment {ring] is shown by transparency in the middle 

 of the mesentery on the under or morphologically posterior surface of the visceral mass. 



15* 



Op 



Text fig. 23. 



