HARDWICKE'S SCIENCE-GOSSIP. 



149 



I 



CHATS ABOUT ROTIFERS. 



(SYNCHCETA GYRINA.) 



N April, 1886, 1 had the good fortune to find a few 

 specimens of this rotifer in a tide pool in the 

 estuary of the Tay, associated with Mytila tavina, 

 Nothocea spinifera, and Distemma raptor, which also 

 were forms new to science. But it soon disappeared 

 from the waters of the Tay, and not a single specimen 

 could be caught, although my fishings were frequent 

 throughout the summer and winter months. But in 

 April, 1887, it has appeared in the same locality 

 in abundance, which proves that it is a spring 

 visitor. 



The corona is convex, with five tufts of vibratile 

 cilia, and bearing four curved styles or bristles, with 

 a pair of side auricles, one on each side, and clothed 



F'g- 77* — Synchceta gyrina. a, female ; b, male. 



•with vibratile cilia. The body is oblong or globose, 

 terminating in a club-shaped process towards the foot 

 with two small toes. Its mouth is furnished with a 

 pair of forcep-shaped jaws, with a dark red eye at the 

 bottom or junction of the jaws. The tube leading 

 from the mouth to the digestive organs is quite 

 visible with a power of 60 diameters. The con- 

 tractile vesicle, which empties and fills once in every 

 45 seconds, is near the region of the foot. 



The water vascular system is very conspicuous in 

 this creature, but to see this, it is necessary to get a 

 specimen under a compressorium under a power of 

 three or four hundred diameters. The lateral canals 

 and vibratile tags in this way are distinctly seen. 



The Synchceta gyrina is a very vigorous swimmer. 

 It is never at rest one moment, or moving in a straight 

 line. Swimming sometimes in wide circles, at other 

 times in circles not much over its own length, it 

 never tumbles or "somersaults" like its marine 



cousin 3". tallica, or its freshwater cousin S.pectinata, 

 or spins round on its toes like its near relation, 

 S. tremula. It is perpetually swimming in circles, 

 hence the reason why I have named it S. gyrina. 



Its food consists of small infusorians of different 

 varieties, which it devours in great numbers. 



The eggs of S. gyrina are quite round, and are 

 deposited at the bottom on the stones amongst 

 conferva and diatomaceae. It differs in this from 

 S. tallica, as it carries its eggs at its foot until hatched. 



I had the good fortune this season to find the male, 

 a very slender creature, not over ^ of an inch long, 

 with a broad corona covered with vibratile cilia with 

 a pair of conspicuous red eyes. It has no mouth or 

 stomach, but a sack (which may be termed the 

 sperm sack), containing granular matter, fills the 

 lower part of the body cavity, with a tube leading to 

 the penis. I was quite certain that this was the male 

 S. gyrina, as I witnessed the process of generation, 

 which takes place while the female is in rapid motion. 

 The male remains in contact over one minute. This 

 operation takes place only with young females. I 

 have never seen a single instance of connection with 

 a full-grown female. 



Length of female 5 l 5 of an inch. 

 ,, ,, male 3J5 of an inch. 



John Hood, F.R.M.S. 



Dundee. 



HOURS WITH A THREE-INCH TELESCOPE. 

 By Captain Noble, F.R.A.S., &c. &c. 



ALL beginners in astronomy should gladly wel- 

 come this excellent little book. Such a work 

 has long been wanted, and attempts have been made 

 to supply the want, yet though these books have each 

 in their way been useful, none of them have been 

 entirely successful. 



This work opens with a clear description of a 

 three-inch telescope, in which the author rightly 

 warns the amateur not to expect to purchase such 

 an instrument of the first quality for £5 ; a most 

 refreshing peculiarity in such a manual, as most 

 popular works which refer to instruments encourage 

 their readers to expect to obtain them for a sum less 

 than half the cost at which they can be manufactured. 

 Then, after describing the telescope, he gives instruc- 

 tions for testing its quality, to which no exception 

 can be taken, but to which an addition should be 

 made. Captain Noble says that "no illuminated 

 haze should appear about bright stars or planets," he 

 should have added if the sky be clear and the object 

 glass is free from moisture, for a very slight want of 

 transparency in the atmosphere or a mere film of dew 

 on the object-glass will cause the best telescope ever 

 made to show a halo round a bright object. 



