Kew: Slime-Threads of Planar ian- Worms. 



r/e 

 3. 



forwards on the new support, the twists move gradually back- 

 wards over the body and are finally transmitted 

 to the thread. Only a limited number of safe 

 descents, Lehnert further notes, can be made in 

 succession ; after four trials, the creature, sup- 

 ported only by a very short attachment, drew 

 itself together and fell to the ground.* Dr. 

 Bergendal has written on the same subject, 

 stating that Bipalium kewense has been seen to 

 descend by threads in the Botanic Garden in 

 Berlin, and that, while keeping specimens in 

 captivity, he had frequently seen the same 

 phenomenon ; he had nothing to add, however, 

 to Lehnert's observations.! 



As regards the smaller land-planarians, Dr. 

 Leidy has a remark for Rhynchodemus sylvaticus% 

 (North America) that the creature secretes a 

 delicate mucous thread ;§ and a few observa- 

 tions have been made by the present writer on 

 Rhynchodemus terrestris, collected under fallen 

 logs in woods in Lincolnshire. My specimens 

 were inch long; and when placed on small 



objects they crawled off like little slugs; some 

 fell without any retaining thread ; but in one Rhynchodemus ter- 

 case, the th read, which was very delicate, did descending from 



J a twig ; drawn from lire 



not fail till it had attained a length exceeding by the writer. Slightly 

 2]/ 2 inches — more than three times the length enlar&ed- 

 of the animal's body. (Fig. 3.) Geodesmus bilineatus, another 

 small species — found in greenhouses in various places in Europe 

 — has been observed by Lehnert ; the suspensory thread, how- 

 ever, never exceeded the length of the creature's body.|| 



In addition to threads used for descent, Lehnert refers to 

 ' bridge-threads,' formed, as he observed in Bipalium kewense 

 and Geodesmus bilineatus, when the animal passes from one 

 object to another, the distance between which does not exceed 



* Lehnert, Archiv fur Naturgeschichte, LVII. ( 1 891 ), pp. 306-50. 



t Bergendal, Studien iiber Turbellarien, 1892, pp. 1-42 (Kongliga Svenska 

 Ifetenskaps-Akademiens Handlingar, XXV.). 



XPlanaria sylvatica. 



\ Leidy, Proceedings of the Academy of Natural Sciences of Philadelphiaj 

 V. (1850-1), pp. 14 1-2. 



II Lehnert, I.e. 



iqoo October 1. 



