222 



NATURE 



[July 5> i 



Again, (hey are furnished with numerous ciliated funnels ; I 

 have not detected them in the nephridia of the anterior segments, 

 but they have been possibly overlooked. These funnels are very 

 abundant ; for example, I counted five in one section on one side 

 of the body. Some of them are distinciy larger than others ; the 

 larger ones were occasionally observed to be connected with a 

 duct which perforated the septum and joined the nephridia of the 

 segment behind. 



In the posterior segments there is a distinct tendency for the 

 nephridial system to become broken up into isolated clumps. 

 It by no means always happened that this tendency to segregation 

 was in relation to the me amerism of the body. On the contrary, 

 the tufts are scattered irregularly in the segments ; and the inter- 

 segmental septa do not always isolate the nephridial tufts which 

 are connected by intraseptal tubules. 



In fact the nephridial system of Perichceta and Megascolides 

 forms a strong support for that view of the origin of the seg- 

 mented from the unsegmented worms that has been so ably 

 argued by Arnold L r ng. 



With regard to the ciliated funnels of Perichceta, it is right to 

 mention that they have been already observed by Dr. Benham 

 in a species from Luzon, though no description has been pub- 

 lished. Prof. Spencer has made the observation that in the 

 posterior region of the body of Megascolides there are a pair 

 of much larger nephridia, which are furnished with a ciliated 

 funnel opening into the segment in front of that containing the 

 nephridium. He believes that these have arisen from the 

 smaller nephridial tufts, and that from them are derived the 

 paired nephridia of such earthworms as Lumbricus. I am quite 

 disposed to agree with Prof. Spencer with regard to these 

 points. I had already made some observations upon another 

 earthworm which exhibits a closely analogous structure. 



In Perichceta aspergillum, as I have mentioned above, some 

 of the ciliated funnels are larger than the others, and are con- 

 nected with a nephridial tuft lying in the segment behind that 

 which contains the funnels. I could not, however, notice a very 

 marked difference in the size of the nephridial tubules themselves. 

 In another species of Perichceta, viz. P. armata, which was 

 characterized some years ago ( Ann. Mag. Nat. Hist , 1 883) by 

 myself, the nephridial system is rather different from that of P. 

 aspergillu?n. Mr. W. L. Sclater, of the Calcutta Museum, has 

 kindly sent me some specimens of this worm which were well 

 preserved. The worm has been lately re-described by Dr. D. 

 Rosa {Ann. Afus. Civ. Genova, 1888), who states that each 

 segment contains a pair of nephridia, opening internally by a 

 funnel which lies in the segment anterior to that which contains 

 the nephridium. So far Dr. Rosa's description is accurate, but 

 there are also innumerable tufts of minute tubules which may or 

 may not be provided with funnels. These appear to be for 

 the most part quite distinct from the large pair of nephridia. 

 The calibre of the tubules of the large nephridia is many times 

 greater than that of the small tufts. The latter open by 

 numerous orifices on to the exterior. 



In the present state of our knowledge it appears to me per- 

 missible to derive the paired nephridia of Luvibricus, Sec, from 

 the network of Perichcrta in two ways, which may both have 

 actually taken place : — 



(1) By the gradual development of a pair of large nephridia, 

 in the way suggested by Prof. Spencer, out of the minute 

 nephridial network, and the gradual disappearance of the latter 

 (which is in the process of disappearance in Pe7'ichceta armata). 



(2) By the gradual breaking up of the nephridial network into 

 tufts of tubules specially connected with the setae, as in Acantho- 

 drilus tnultiporus, and by the disappearance of all but two of 

 these. Dr. Benham's interesting form, Brachydrilus, which has 

 two pairs of nephridia in each segment, offers an intermediate 

 condition in this reduction. 



To assume that the ordinary condition of the nephridial 

 system of earthworms has been derived in these two ways, 

 renders the mutual affinities of certain earthworms easier to 

 understand. For example, Perionyx (which is so nearly allied 

 to Perichceta in most respects, but differs in having nephridia of the 

 Lumbricus pattern) may have been derived from Perichceta 

 directly via some such form as P. armata without having passed 

 through an " Acanthodrilus stage" ; again, Deinodrilus, which 

 is intermediate in many characters between Perichceta and 

 Acanthodrilus, is also, as I shall hope to show later, inter- 

 mediate in the arrangement of its nephridia, and may therefore 

 represent a stage in the evolution of Acanthodrilus. 



Zoological Gardens, N. W. Frank E. Beddard. 



THE " AVOCET" ROCK. 



THE circumstances attending the loss of the s.s. 

 Avocet and Teddington towards the southern end 

 of the Red Sea in the year 1887, and the subsequent 

 finding of the small coral patch on which it is probable 

 they both struck, are of interest, and deserving of record 

 as showing the necessity for very close examination of 

 seas where corals flourish, and the difficulties experienced 

 in finding a small patch at a distance from land, when 

 neither discoloration nor break of sea aid the searcher. 

 It should be premised that the area between the Zebayir 

 Islands and Jebel Zukur, in which this rock lies, had 

 never been properly sounded, only a few scattered depths 

 having been obtained. It is crossed yearly by hundreds 

 of steam-ships — the majority of them British — and has 

 always been accounted as deep, safe water. 



On the 4th of March the Avocet was steaming south- 

 wards — with another steamer, the St. Oswald, with which 

 she had kept company for some hours, not far from her — 

 a strong head-wind and heavy short sea prevailing at the 

 time. At about 8 a.m. a shock was felt, succeeded by 

 two others, and shortly afterwards water was found to be 

 coming in. It being evident that the ship would go down, 

 the St. Oswald was signalled, and after a little time the 

 crew of the Avocet were taken off by her, and the latter 

 sank. A Court was held at Aden, and the evidence 

 taken before it showed that the shock had been slight, 

 one witness stating that he thought something had gone 

 wrong in the engine-room ; and another, that it was a 

 heavy sea that had struck the ship. The verdict was 

 that the ship had struck on an unknown rock in latitude 

 14 21' N., longitude 42° 38' E., the position given by the 

 master. No evidence was given to prove this position ; 

 but the fact of the St. Oswald being in company, and of 

 other steam-vessels passing on either side of the two 

 ships both just before and just after the accident, seemed 

 to show that they must have been in the straight track, 

 and that the position was not far wrong in longitude at 

 any rate. H.M. surveying-ship Flying Fish, arriving at 

 Aden shortly after the inquiry, spent some days on the 

 suspected ground, and found nothing but deep water,, 

 over a hundred fathoms being found in the position 

 given. 



Those who have the responsibility of the issue of charts 

 for the guidance of navigators may be pardoned if they 

 are extremely sceptical and difficult to- convince in the 

 matter of new rocks in the great highways of traffic. So 

 many instances occur of reports which on investigation 

 prove to be erroneous— sometimes in the whole, some- 

 times in part (as of the position, for instance) — that very 

 good evidence is required before a report, which seems 

 in itself improbable, can be accepted, and one of Her 

 Majesty's ships sent— perhaps from a long distance, and 

 from other important duties — to spend many days in a 

 search. In this case there was no doubt of the ship having 

 foundered ; but the cause of the disaster was somewhat 

 doubtful, and her position was unsubstantiated. It was 

 evident, however, that if she had struck bottom it must 

 be a very small rock, as the presence of other vessels 

 prevented the supposition of a wrong course. 



The Avocet was partly laden with railway iron, she was 

 pitching in a heavy sea, and the evidence of external 

 injury was not convincing. Altogether it seemed more 

 probable that some of this heavy material had fetched 

 way and injured the ship from inside than that a rock, 

 could exist in the very track of the heavy trade of the 

 Red Sea. The Admiralty therefore announced that they 

 would order no further search until these points were 

 cleared up, and the Board of Trade consented to order a 

 further inquiry. 



The witnesses were collected, and the Court sat on 

 June 10, but before any further proceedings could take 

 place a telegram was placed in the hands of the President 



