Land-Nemertean from the Bermudas. 411 



the object of these lines is only to show that in America also 

 land-Nemerteans exist. Hitherto they were only known from 

 the Pelew Islands, where Semper has found another Trema- 

 cephalid, to which he has given the name of Geonemertes 

 jpelceensis. I think it is highly probable that land-Nemerteans 

 exist to a greater extent in tropical countries than has hitherto 

 been supposed, and that, from their hidden life and the im- 

 possibility of preserving them, they have hitherto escaped the 

 attention of ti'avelling naturalists. Especially in such islands 

 as the Bermudas, where the earth of the lower grounds contains 

 a great deal of salt, it may easily be imagined how marine 

 animals have taken to terresti-ial habits ; and it was interesting 

 for me to see that our Tetrastemma when put into salt water 

 would live there for twenty-four hours, but when put into fresh 

 water died after a few hours time. Fresh water, however, 

 poured over the earth which contained them did not damage 

 them in the least. 



I may here also add that on our cruise from the Bermudas to 

 the Azores I foimd jparasitical Nemerteans on Nautilograpsus 

 minutus, one of the gulf-weed crabs. They were small brownish 

 animals, and occupied especially the underside of the crab. 

 Tinder the abdomen of which I found most of them. They did 

 not exceed the length of 2 millims. ; and in none of them could 

 I see genital organs. In fig. 4 I have figured one of these 

 small parasites, which probably also belong to the genus 

 Tetrastemma^ though the second pair of eyes is only puncti- 

 form, situated on both sides of the proboscis. Nervous system 

 and digestive apparatus do not present any thing particular ; 

 the proboscis (fig. 4, p/-j)r^) is remarkable for its shortness. 



I do not think that these worms attain their full size on the 

 crab ; but believe them to be young parasitical stages of some 

 Nemertean which possibly lives on the gulf-weed. In this 

 group of worms no case of parasitism has, as far as I know, 

 been mentioned before. 



H.M.S. 'Challenger,' Cape Town, 

 November 1873. 



EXPLANATION OF PLATE XVU. 



Fig. 1. Young male of Tetrastemma agricola. Low power, jjr^-pr*, suc- 

 cessive portions of the proboscis — ^r' entrance, p7-^ papillar por- 

 tion, pi^ pouch of stylets, pr* glandular portion ; ca, muscular 

 entrance of the glandular portion ; o, mouth ; i, intestine ; 

 a, anus ; g, ganglion ; w, lateral nerves. 



Fig. 2. Part of the male's proboscis. The same letters as above. High 

 power. 



Fig. 3. Part of the female's proboscis. High power. 



Fig. 4. Young parasitical Tetrastemma from Nautilograpsus minutus. 

 High power. Letters aa above. 



30* 



