io6 



SCIEXCE-GOSSIP. 



colour is, however, darker in some parts than 

 in others, the darker spots being statoblasts, or 

 small buds produced on the funiculus, which 

 continue clustered together by their marginal 

 spines until they are set at liberty by the destruc- 

 tion of the colony, and, attaching themselves to the 

 weeds, in time produce a new generation of life. 



Around the convex upper margin of the caensecium 

 or dermal system, we have a regular series of 

 Polypides, while in the central portion there are 

 none. The flattened muscular disc of the under 

 surface, is the means by which it attaches itself to 

 the aquatic plants, and by which it is enabled to 

 move from place to place. Projecting outwards 

 from the mass are the tentacles, some seventy to 

 eighty in number. They are hollow as in many 

 similar forma, and communicate with the interior 

 perigastric mass. These tentacles are covered 

 with extremely fine cilia, which, by reason of 

 the currents they produce, are the means of 

 supplying the colony with food, and by a directly 

 opposite motion of the cilia on the other side 

 of the tentacles, are the means of producing 

 respiration. 



The form of the individual Polypides will be 

 better understood by reference to fig. 2 than by 

 any written description. They will be seen to 

 consist of a sac (g), the only features external, 

 which are the tentacles or ciliated organs of re- 

 spiration. Within the sac is an alimentary canal, 

 marked 6, within which is combined the oesophagus, 

 stomach and intestines, and which will be seen to 

 double round and form an anus at c, not far distant 

 from the mouth. Running through the whole 

 length of the animal are the retractor muscles (e) by 

 which the tentacles are withdrawn within the sac 

 for protection on any alarm of danger, as seen in 

 fig. 3. The reproductive organs he on the lower 

 portion of one of the sides, and are represented in 

 the sketch by f; while the small protrudence (d), 

 below the tentacles on the side nearest the anus, is 

 a nervous ganglion, or organ of sensation. In 

 Cristatella, unlike the other species, there is only 

 one investing sac, the endocyst, the ectocyst being 

 absent. The epistome, or tongue-like organ, is 

 small, and in many cases very indistinct. In 

 addition to the muscles by which the tentacles are 

 withdrawn within the sac, the muscular system also 

 provides for the rotatory action of the crown, and 

 those rigid states in which the Polypide remains 

 when the tentacles are drawn into the interior. 



Reproduction is effected by ova, by gemmae, and 

 by the statoblasts already referred to in this paper. 

 The ova, after escaping from the ovary into the 

 perigastric cavity, receive their impregnation from 

 free spermatozoa, and most probably escape by the 

 rupture of the cells. The gemmae spring from the 

 endocyst as projections into the perigastric space, 

 but after a time appear as vesicles projecting from 



the exterior, out of which the Polypides at length 

 develop. 



Cristatella mucedo prefers for its home a clear 

 lake or running water, and is rarely found where 

 the water is very muddy. As an exception to the 

 general rule they are not at all partial to dark 

 habitations being often found flourishing in bright 

 sunlight, hence there is not the necessity to guard 

 against the admittance of light when keeping them 

 alive in a vessel of water, as with other species of 

 Polyzoa. "When keeping them for examination 

 great care must be taken to supply them with an 

 abundance of food, for they are most voracious 

 feeders, and need constant attention. 



Nothing is more interesting than to watch the 



gradual development of this wonderful object, and 



mark the stages which the Queen of Polyzoa has 



to pass through before her development is complete. 



Eversley, 123, Pembroke Road, Clifton. Brisiol ; 



31st May, 1894.. 



BIRD NOTES. 

 By H. Mead-Briggs. 



Cuckoo pausing ox first note. — Can you tell 

 me if it is a usual occurrence for cuckoos to pause 

 on the first note ? I have generally found such is 

 the case towards the end of the season. On the 

 23rd of April I heard one that repeatedly stopped 

 short on the word " cuck " — a very early date. 



Piebald Rook. — A curious specimen of this 

 year's rook (Corvus frugilegus) was shot at Stour- 

 mouth on May 5th, having five white primary 

 feathers in each wing, the base of bill and throat 

 white, also white claws and partly white toes ; eyes 

 grey. In every case it is to be noted that the 

 extremities are white, except the tail, which is the 

 usual colour. 



Jackdaw and Young Ducks. — A farmer in this 

 neighbourhood has recently lost ten young ducks, 

 which he avows have been killed by a jackdaw. I 

 have personally interviewed him on the subject, 

 having no doubt, however, in my own mind that a 

 hawk or a rat was the cause of the mischief; but 

 he and a farm-hand still stick to its being a jack- 

 daw, as they have seen it. The nest was pointed 

 out to me in a hole in a tall elm tree, and, upon 

 climbing up, I certainly found a jackdaw's nest ; 

 but no evidence of ducks, nor can I say I expected 

 to. According to the farmer's statement the ducks 

 are killed and partly devoured by this strange bird 

 on the spot, never in any case being carried away, 

 and I think this in itself ought to be one very good 

 reason for supposing it to be the work of rats, for a 

 jackdaw would hardly kill the ducks, unless for his 

 brood, which were far too young in this case to 

 appreciate such delicacies. A hawk would have 

 hardly left his spoil in every instance upon the 

 scene of slaughter, whereas a rat might, as the 

 object of the rat is to get at the crop and eat the 

 meal and other food of the duckling. I do not 

 doubt that the jackdaw had been having his picking 

 off the dead victims ; but it is highly improbable 

 that he killed them in the first instance, although I 

 believe rooks have been known to do so. Can any- 

 one enlighten this British farmer on the subject ? 

 17. Si. OizrsC: Place. €.: ::r : :.;; . 



