HARDWICKE'S SCIENCE-GOSSIP. 



ii 



head, and from what may be termed a vascular rete 

 mirabile enveloping the stomach and intestine, and is 

 divided behind, g, and distributed to the branchial 

 processes. From these, vessels again converge into 

 a dorsal artery, following the undulations of the 

 alimentary canal, and conspicuous from an intrinsic 



portions, two as above and a third behind, and 

 the somites in the last portion have evidently been 

 most recently formed. 



A double abdominal nervous cord is plain enough 

 all along below the longitudinal vein ; the brain is 

 less definitely seen ; there are also two minute bodies 



I 



Fig. s. Structure of Dero- 



-a freshwater Annelid, a, b, c, posterior extremity; d, head ; e, seta; ;/, g, vessels of 

 the head and branchia?. 



metility which the vein has not. The course of the 

 dorsal vessel is somewhat the same as the ventral. 

 When it lies above the middle part of the alimentary 

 canal it forms the beautiful network already men- 

 tioned, and is, besides, connected in each somite or 

 section of the body with large contractile loops, 

 apparently distributing the blood to the viscera and 

 parietes of the body, but, according to Perrier, not 

 immediately connecting the two vessels. The little 

 worm is well supplied with abdominal tufts of sigma- 

 shaped hooks for crawling, and also with lateral or 

 dorsal seta? for swimming, the former are bifid at their 

 extremes, e. 



The mouth, d and f, is furnished with a bulbous 

 tongue, which can be protruded a little in feeding ; 

 both here and behind the alimentary canal is ciliated ; 

 there is some appearance of a stomach at about the 

 seventh and eighth somite of the body, and here is 

 the liver incorporated with the canal, and also 

 in the same region the ovaries, &c. ; the intestine is 

 dilated in each division of the body, and connected 

 by bands with its parietes. 



We have no sufficiently matured observations to 

 offer as to the development of the ova in the Dero. 

 Perrier describes its fissiparous mode of increase, but 

 the following account differs somewhat from him. 

 Sometimes a long Dero, say of fifty joints, very 

 evidently divides into two, a respiratory disk for the 

 anterior secondary worm, and a head for the posterior 

 one being formed at the place of disjunction ; here 

 the anterior portion, containing the ovaries, probably 

 becomes the germ-mother, and perhaps winter-nurse. 

 In other cases the individual Dero presents three 



at the sides of the brain, probably acoustic, a few 

 darker coloured spots more forward, and apparently 

 lateral oral ganglia. The animal is sensitive to a 

 very slight concussion of the vessel in which it lives. 



PLANT-HUNTING AT BARMOUTH. 

 By J. Percival. 



HAVING read with great pleasure the interest- 

 ing notes of your correspondent Horace 

 Pearce, F.L.S., of the flora of the neighbour- 

 hood of Cader Idris, I wish to add, by way of 

 supplement, a few of the plants that came under my 

 observation during the summer of 1876, for I find 

 that he has omitted a great portion of the rarer 

 species. Walking along the road in the direction of 

 Llanaber may be seen Parietaria officinalis, Eckium 

 vidgare, Clinopodium vidgare, Origanum vidgare, 

 Eaonymus Europazts, and Aspleninm lanceolatum. 

 This latter plant may be found for a mile on old walls 

 and rocks, and in far greater abundance than its near 

 ally, Aspleninm Adianlum-nigrum. It may also be 

 found on walls overlooking Barmouth, and also for 

 two miles on the Dolgelly road from Barmouth; 

 turning into the harbour, a little short of a mile from 

 Barmouth, it may be seen there very fine and abun- 

 dant. A little further, on rocks facing the sea, may 

 be gathered Rubia peregrina, or the common Mad- 

 der ; growing also with it is Inula conyza, or the 

 " Ploughman's Spikenard " ; another mile further on 

 brings you to Carex extensa and Tamarix Gallica ; 

 and also Spircca salicifolia : both the latter have, no 

 doubt, been planted, but probably they are as wild 



