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HARDWICKE'S SCIENCE-GOSSIP. 



[April 1, 1S69. 



LAND LEECHES. 



/"VUR correspondent " G. Pi." will be glad to 

 ^ learn that by sending to Mr. Buckland the 

 land leeches, the habits of which so puzzled him, 

 he has contributed to the settlement of a very in- 

 teresting question connected with the natural his- 

 tory of this country. When Dr. Gray, in 1S50, 

 claimed for Trocheta subviridis a place in the 

 British Fauna, [in consequence of Mr. Hoffman 

 having found one individual of this species in the 

 Regent's Park, it was objected to his supposition 

 of its being indigenous in Britain that the ovum, 

 or the leech while young, might have been taken 

 into the viscera of a deer or other animal in its own 

 native country previously to its being shipped for 

 England. Dr. Murie, in fact, believed that he had 

 found another specimen in the viscera of a Moluccan 

 deer dissected at the Zoological Society's Gardens 

 in 1865, and described it in a paper which he read 

 before that Society in November of the same year, 

 as being identical with that previously fouud by 

 Mr. Hoffman and commented on by Dr. Gray. 



When I ventured to state my opinion that the 

 leccbes sent up to us by " G. B." were Trocheta 

 subviridis of Dutrochet, many eminent zoologists 

 were very naturally inclined to doubt the correct- 

 ness of my identification of them. But I am glad 

 to say there is no longer any doubt about it. " G. 

 P." was kind enough to send me fresh specimens, 

 and I have submitted them to Dr. Gray and Dr. 

 Baird, of the British Museum, and also to Dr. 

 Murie. They all agree that the leeches in question 

 are of the species to which I assigned them, and 

 Dr. Baird has kindly given me permission to pub- 

 lish for the benefit of our readers the following 

 letter which I received from him : — 



" My dear Sir, — The land leeches which you 

 brought here yesterday belong certainly to the 

 Trocheta subviridis of Dutrochet. I put them into 

 weak spirits to kill them, but after placing them in 

 stronger spirits, the colour has nearly gone from the 

 leeches and imparted itself to the spirits, which is 

 now of a fine green hue ! The specimen sent some 

 few years ago by Mr. Bartlett from the Zoological 

 Gardens, is also a true Trocheta; but the one 

 brought by Dr. Murie, and which he has described 

 in the Zoological proceedings as the Trocheta sub- 

 riridis, is not a Trocheta at all, but must belong, 

 from the structure of the oral and especially the 

 ventral sucker, either to a peculiar species of 

 Jhniiopsis, or to anew genus not hitherto described. 

 I thought at the time when Dr. Murie brought the 

 specimen here that it might belong to the genus 

 Trocheta, but now I find it does not. If you can 

 procure for us some more specimens I should be very 

 glad, and any other species of the suctorial annelides 

 will be thankfully received. Yours very truly, W. 

 Baird (British Museum, March 6th, 1S69)." 



I have also received an interesting letter on the 

 subject from the Rev. W. Houghton : — 



"My dear Sir, — I am very much obliged to 

 ' G. R.' and to yourself for the two leeches which 

 I received on Saturday night. They were quite 

 lively when I turned them out. One I have dis- 

 sected, the other remains for future observations. 

 There is not the slightest doubt as to the species, 

 it is the veritable Trocheta subviridis of Dutrochet, 

 and thus your first opinion is fully confirmed. As 

 I said, this discovery is interesting, as it proves 

 that this sub-terrestrial species is an undoubted 

 member of the British fauna. Moquin-Tandon 

 enumerates as many as six varieties of this leech ; 

 they only differ in colour. The two sent to me are 

 the common variety ; one was about six inches long- 

 when extended, the other was smaller. I observed 

 on the specimen I dissected nine very minute black 

 eye-spots, five on the first segment and four on the 

 third ; the normal number is eight, but in the leech 

 family the eye-spots often vary. I could not detect 

 the teeth which Moquin-Tandon has described and 

 figured as characteristic of Trocheta ; I have no 

 doubt they too are occasionally absent; neither 

 eyes nor teeth can be of any real use to the pos- 

 sessor. The digestive apparatus in this species 

 consists of a muscular triple-folded oesophagus, 

 stomach with no coecal appendages, and straight 

 simple intestine, showing in this respect a closer 

 affinity to Nephelis than to its apparently more 

 allied genera, Hcemopsis, Aulastoma, and Hirudo. 

 Neither of the individuals seemed at all at home 

 when placed in a vessel full of water ; they dropped 

 to the bottom, and after moving about for a time 

 fixed themselves there. I could not prevail on 

 either of them to swim. Dutrochet considered 

 Trocheta entirely terrestrial, but M. Moquin-Tandon 

 asserts that he has kept many individuals alive in 

 water more than fifteen days. Eurther observations are 

 wanting to clearup this point. The allied generaswim 

 readily enough, and, as we know, live in the water 

 for the most part. Is Trocheta a curious exception 

 to the rest ? If ' G. R.' should meet with more 

 of these leeches about the beginning of June, and 

 would kindly send me some, I should be obliged to 

 him. About the middle of that month the leeches 

 lay their eggs or cocoons, in which the young are 

 developed. Again thanking you and ' G. R.' for 

 the trouble you have taken, Very sincerely yours, 



" W. Houghton." 

 Dr. Gray's description of Trocheta subviridis as 

 belonging to the British fauna is thus confirmed. 

 The individuals which have led to this result were 

 found near Horsham ; but I have little doubt of our 

 soon receiving them from other localities. "G. R." 

 says he has heard of them in Hants, and I am in- 

 formed by one of my own relatives that at Linfield, 

 in Sussex, about twenty-five years ago, land leeches 

 were so abundant in the fields and on the footpaths 



