MELICERTAD.E. 81 



[This very striking species I found on leaves of Anacharis alsinastrum, which had 

 been growing for months in a glass jar in my study- window. 



The body and corona do not vary much from those of other species. In the act of 

 expanding, the summit of the head becomes sub-conical, and is seen to terminate in two 

 small hooks having a common stem, which remind the observer of the protruding head 

 of Melicerta ringens (fig. lb). When unfolded, the corona does not much exceed 

 the greatest diameter of the body : it appears to form a complete uninterrupted circle. 

 A small round knob on a conical eminence constitutes a ventral antenna ; a little 

 below which is seen the mastax ; and, about as much below this, but on the opposite 

 side to the antenna (the dorsal side), the cloaca is bounded by a minute wart. The body 

 is of the usual proportions, but the foot is of enormous length, being about thrice as long 

 as the trunk and head. It is rather stout (about half the greatest diameter of the body), 

 and of uniform thickness throughout ; thrown for its entire length into transverse 

 close-set wrinkles. These were not obliterated nor perceptibly diminished by the 

 greatest extension that I witnessed ; so that, if this corrugation is a provision for 

 indefinite elongation at pleasure, as one must suppose, then the foot would seem capable 

 of stretching to a length more than ten times as great as I have represented ! Yet I have 

 seen it on repeated occasions contracted in an instant to a condition in which it was not 

 more than half the length of the body, or one-sixth of its former length. 



The investing tube is reduced to extreme insignificance. The one that I saw would 

 not hold half the body, even if it had no foot. It was invisible, save for a few 

 irregular opaque masses here and there, and for two or three eggs adhering to the 

 margin. As if indifferent to concealment, the foot was attached to a point not near the 

 bottom of even this short dwelling. 



The trunk is transparent, but tinged with umber-brown. Here and there, within, 

 were multitudes of very small air- (or oil-J globules agglomerated into long masses, which 

 looked like patches of blue-black hue, and had a curious appearance. When I first saw 

 the specimen, two eggs were already laid, and presently a third was added, but not under 

 my actual gaze. The eggs were all of a clear yellow, minutely granular. 



The manners of this creature are as odd as its figure. It is not by any means in- 

 tolerant of exposure : though sensitive, shutting up and violently contracting on a very 

 slight shock or jar, yet hi a moment it is again stretched to its length, and quickly has 

 its corona expanded. The foot is endowed with an extreme flexibility and muscular 

 power, for the animal is constantly (I will not say swung, but) shot, from side to side ; 

 just as the body of a snake or of a writhing worm is jerked about in tortuous evolutions. 



While I was examining and delineating this example, another appeared, in all essen- 

 tial points agreeing with it, but quite destitute of any ajrology for a case, the foot being 

 unattached to any object ; the creature being loose hi free water, but lying on the same 

 leaf of Anacharis. The male has not yet been observed. — P.H.G.] 



This species in many points resembles Ehrenberg's Ptygura Melicerta. The two 

 agree in the small corona, cylindrical body, dorsal hooks, single ventral antenna, many- 

 toothed jaws, and inconspicuous or absent tube. But the prodigious length and ex- 

 tensibility of the great ringed foot of CE. serpentinus, and the animal's extraordinary 

 actions, none of which are mentioned by Ehrenberg, show it to be a different creature. 

 If Ehrenberg had seen only a solitary specimen for a few minutes, in a contracted 

 state, the two might have been supposed to be the same ; but he distinctly says that he had 

 met with many examples. Besides, Herr Eckstein has also found Ptygura Melicerta 

 more than once ; and, although he has not seen the expanded corona, his description 

 and figure in all other respects agree with Ehrenberg's. 



From the descriptions given by Ehrenberg and Herr Eckstein I am inclined to think 

 that Ptygura is an GScistes ; but it is impossible to determine this till the corona has 

 been thoroughly studied. 



Length. Not recorded. Habitat. On a leaf of Anacharis alsinastrum in a fresh- 

 water aquarium (P.H.G.). 



H 



