166 QUARTERLY CHRONICLE. 



the Holothuria is that of Enchelyophis (Joh. Miiller j, which 

 is entirely destitute of pectoral fins. 



As to Crustacea, M. Semper mentions, besides some small 

 Copepods, t\vo species of the genus Pinnotheres, which lives, 

 as is well known, ordinarily as a parasite in I.amellibrancha. 

 It is remarkable that these two species are parasitic in the 

 same Holothuria, where they are constantly found in the 

 right lung, that is to say, in that which has no connection 

 with the enteric vessels. Sometimes the lung which lodges 

 a Pinnotheres is completely atrophied, but in this case 

 another is developed in an abnormal position. 



The Molluscs number several parasites of Holothurise ; and 

 firstly the celebrated Entoconcha mirabiUs, discovered by 

 Joh. Miiller in the Synapta d'ujitata of Europe, has its coun- 

 terpart, not now in a Synapta, but in a Holothurian pro- 

 perly so-called, found in the Philippines. This extraordinary 

 Gasteropod has been christened by M. Semper by the name 

 Entoconcha MilUeri. It appears to be restricted, as a rule, 

 to the cloacal region. Mr. Cumming long since pointed out 

 the presence of Eulima in the stomach of the Holothuriee ; 

 but it appears to have been generally considered that these 

 Gasteroi)ods had been swallowed by the Echinoderms. This 

 opinion is erroneous. M. Semper possesses two or three spe- 

 cies, which he has found alive and crawling joyously in the 

 intestine of the Holothuria?. These species are exceedingly 

 active in their movements, in opposition to the epizoic spe- 

 cies, the foot of which is in general buried in the skin of 

 their host. The sole food these Gasteropods have at their 

 disposal is the chyme, or indeed, the secretions of the intes- 

 tinal epithelium. They may, therefore, well be called para- 

 sites. It is not improbable that conchologists are wrong 

 when they state that the Eulimse and the Stylifers (which live 

 among the spines of Cidaris and other Echinids) do not ob- 

 tain tbeir food from their hosts. They appear to forget that 

 the spines of the Echinoderms are not merely cuticular forma- 

 tions, like the shells of molluscs. Parasitism is clearly evi- 

 dent in a species of Eulima found by M. Semper in a cavity 

 of the skin of a Holothuria, of the genus Stichopsis. During 

 the life of the Echinoderm the shell is nearly entirely hidden 

 in the skin, the summit of the spire alone slightly protrud- 

 ing. If one tries to remove it a strong resistance is felt. 

 But when the Holothuria is moribund, one can succeed in 

 withdrawing the mollusc armed with a long and fine thread, 

 which, in large individuals, at any rate, can penetrate right 

 into the cavity of the body of the Holothuria. This thread is 

 nothing else than the greatly elongated proboscis of the mol- 



