178 



NA rURE 



[yiine ::4, iSfc'o 



meeting of Thursday (your clay of publication). The 

 specimens on which I worked were given to me by Mr. 

 Sowerby, the secretary of the Botanical Society, who dis- 

 covered the animal, and in reply to my particular inquiry 

 as to whether any naturalist had been charged by him 

 with the task of working it out, he said that no one had, 

 but that he had freely given specimens to several gentle- 

 men. He asked me to find a name for the new Medusa, 

 and I promised to send him a copy of what I should 

 publish on the subject. 



I hold it to be a very excellent thing that there is a 

 certain kind of honour attaching to the priority of de- 

 scription of nevT and important genera among zoologists. 

 It appears to me to give a zest and stimulus to hard work 

 in the cause of zoology which is very far from being a 

 thing to be despised. I confess to having worked at that 

 INIedusa day and night when I first obtained it, with the 

 object of having the pleasure and honour of being the 

 first to e.xpound its structure to my brother naturalists. 



At the same time I wish to say that had I known that 

 so esteemed and veteran a zoologist as Dr. Allman was 

 an.xious to associate himself with this little novelty, 1 

 should have felt it to be only consistent with the great 

 personal regard which 1 entertain for him to abstain from 

 any publication on the subject until he had come forward 

 to provide the new Medusa with a name, which I am 

 sure would have been a prettier one than my somewhat 

 unwieldy proposaL 



Under these circumstances it gives me great pleasure 

 to say that, so far as I am concerned, I am quite willing 

 to give up the name Craspelacustes, and to adopt Prof. 

 AUman's name for the new freshwater Medusa whenever 

 he may publish it. 



I have no doubt that we shall shortly hear a great deal 

 more about the freshwater Medusa, since it is very 

 abundant in the Regent's Park lily-house, and since Mr. 

 Sowerby, with true scientific hberahty and courtesy, 

 freely allows naturalists who desire specimens to provide 

 themselves with such, and has very properly placed no 

 restriction upon their study or on the publication of 

 results. E. Ray L.^nkester 



Oh ^^ Liinnccodium victoria^' a Hydroid Mt\hisa of 

 Fresh Water 



A SHORT time since I received from Mr. Sowerby, 

 Secretary of the Royal Botanical Society, a letter 

 informing me of the occurrence of certain Medusoid 

 organisms in the warm-water tank devoted to the culti- 

 vation of the Victoria regia in the Gardens of the Society. 

 The letter contained a request that I should examine the 

 animals with a view to their determination ; Mr. Sowerby 

 accompanied it with rough sketches, and offered to place 

 specimens at ray disposal for investigation. 



The discovery of true freshwater Medusas was so 

 startling a fact that I lost no time in calling on Mr. 

 Sowerby, with whom 1 risited the tank, and carried away 

 such specimens as were needed for examination. 



The water in the tank had then a temperature of 86° 

 F., and was literally swarming with little Medusa:, the 

 largest of which measured nearly half an inch in trans 

 verse diameter. They were very energetic in their 

 movements, swimming with the characteristic systole 

 and diastole of their umbrella, and apparently in the very 

 conditions which contributed most completely to their 

 well-being. 



As it now became evident that the Medusa belonged to 

 a generic form hitherto undc scribed, I prepared for the 

 Linnean Society a paper containing the results of my 

 examination, and assigning to the new Medusa the name 

 of Liinnocodiiitn vietoria (Ktfivi], a pond, and Kadav, a bell). 

 This was received and recorded by the secretaries on 

 June 14, and read at the next meeting, on the lyih.'- 



Some facts in addition to thjse contained in my original paper arc 

 -included in the present communication. 



The umbrella varies much in form -with its state of 

 contraction, passing from a somewhat conical shape with 

 depressed summit through figures more or less hemi- 

 spherical to that of a shallow cup or even of a nearly flat 

 disk. Its outer surface is covered by an epithelium com- 

 posed of flattened hexagonal cells with distinct and 

 brilliant nucleus. The manubrium is large ; it commences 

 with a quadrate base, and when extended projects beyond 

 the margin of the umbrella. The mouth is destitute of 

 tentacles, but is divided into four lips, which are everted 

 and plicated. The endoderm of the manubrium is thrown 

 into four strongly-marked longitudinal plicated ridges. 



The radial canals are four in number ; they originate 

 each in an angle of the quadrate base of the manubrium, 

 and open distally into a wide circular canak Each radial 

 canal is accompanied by longitudinal muscular fibres, 

 which spread out on each side at the junction of the radial 

 with the circular canal. 



The velum is of moderate width, and the extreme 

 margin of the umbrella is thickened and festooned, and 

 loaded with brownish-yellow pigment cells. 



The attachment of the tentacles is peculiar. Instead 

 of being free continuations of the umbrella margin, they 

 are given ofi' from the outer surface of the umbrella at 

 points a little above the margin. From e.ach of these 

 points, however, a ridge may be traced centrifug.ally as 

 far as the thickened umbrella margin ; this is caused 

 by the proximate portion of the tentacle being here 

 adnate to the outer surface of the umbrella. It holds 

 exactly the position of the " mantelspangen " qx pe)-onia, 

 so well developed in the whole of the Narcomedusa; of 

 Haeckel, and occurring also in some genera of his 

 TrachomeduiK. Its structure, however, diiiers from that 

 of the true feronia, which are merely lines of thread- 

 cells marking the path travelled over by the tentacle 

 as the insertion of this moved in the course of meta- 

 morphosis from the margin of the umbrella to a point 

 at some distance above it, while in Limnocodium the 

 ridges are direct continuations of the tentacles whose 

 structure they retain. They become narrower as they 

 approach the margin. 



The number of the tentacles is very large in adult 

 specimens. The four tentacles which correspond to the 

 directions of the four radial canals or the perradial ten- 

 tacles are the longest and thickc-t. The quadrant which 

 intervenes between every two of these carries, at nearly 

 the same height above the margin, about thirteen shorter 

 and thinner tentacles, while between every two of these 

 three to five much smaller tentacles are given oft' from 

 points nearer to the margin, and at two or three levels, 

 but without any absolute regularity; indeed, in the older 

 examples all regularity, except in the primary or perradial 

 tentacles, seems loit, and the law of their sequence ceases 

 to be apparent. 



I could find no indication of a cavity in the tentacles ; 

 but they do not present the peculiar cylindrical chorda- 

 like endodermal axis formed by a series of large, clear, 

 thick-walled cells which is so characteristic of the solid 

 tentacles in theTrachomedussand Narcomedusa;. From 

 the solid tentacles of these orders they difler also in 

 their great extensibility, the four perradial tentacles 

 admitting of extension in the form of long, greatly- 

 attenuated filaments to many times the height of the 

 vertical axis of the umbrella, even when this height is at ' 

 its maximum ; and being again capable of assuming by 

 contraction the form of short thick clubs. Indeed, 

 instead of presenting the comparatively rigid and im- 

 perfectly contractile character which prevails among the 

 Trachomedusa; and the Narcomedusa;, they possess as 

 great a power of extension and contraction ai may be 

 found in the tentacles of many Leptomedusa; (Thau- 

 mantida;, t&c.). These four perradiate tentacles con- 

 tract independently of the others, and seem to form a 

 different system. All the tentacles are armed along their 



