2SG 



Part TIL — Eleventh Annual Report 



Few groups of invertebrates are more generally distributed in their pelagic 

 larval condition than the Annelids, which are seldom absent from the 

 tow-nets, especially the trawl-like bottom-net. They have been elsewhere 

 referred to,* so that on the present occasion it is only necessary to observe 

 that from January to December they are present at one stage or another, 

 and afford a constant source of food for the smaller fishes. Perhaps the 

 most conspicuous family is that of the Spionidae, in which is the well- 

 known borer in rocks and shells, viz., Polydora ciliata. 1 The curious 

 larva of Polygordius is not uncommon in July and August, and Tovnaria 

 and Mitraria also occur. 



In our waters the characteristic pelagic Alciopidse of the southern seas 

 are absent, their place being taken by the ubiquitous Tomopteris, and in 

 inshore waters by the active sexual forms of Autolytus, the majority 

 bearing ova ; and by an occasional ffeteronereis-form in spring. 



The absence of accurate knowledge concerning the development and 

 life-history of the common cross-fish (Uraster rubens) has for many years 

 been a conspicuous blank, and it was well known that no adult had ever 

 been seen bearing eggs externally. It thus appeared to differ wholly from 

 the abundant tidal form Cribrella oculata and the somewhat rarer Asterias 

 Mulleri,-\ which is not uncommon at St Andrews under stones in rock- 

 pools, both of which carry the eggs and larvae over the mouth. The recent 

 researches of Mr Field on Asterias rubens % clears up the difficulty, 

 for it is found that the larvae are pelagic, and form in St Andrews Bay 

 part of the teeming multitudes of larval Echinoderms, which in the form 

 of Bipinnarians, Brachiolarians, Auricularians, and Plutei, characterise the 

 warmer months. The vast myiiads of the minute eggs of the common 

 cross-fish are given off in May and June. 



The irregularity in the appearance of the larger medusae, e.g., Aurelia 

 and Cyanea, in multitudes, has again been illustrated during the last 

 season, when comparatively few entered the bay, whereas in 1891 both 

 were common. A knowledge of the effects of currents and other facts 

 connected with their distribution is not yet sufficiently accurate to enable 

 us to make an explanation of the causes of such variations. The hydro- 

 medusae, on the other hand, seems to be more regular, the majority oc- 

 curring in June, July, and August, while Tima and Aglantha are char- 

 acteristic of the winter months. In April the medusoid Hyboeodon gene- 

 rally makes its appearance, and continues to the end of summer. They 

 are conspicuous by their four carmine ocelli, and their two tentacles have 

 batteries of thread-cells. Large buds spring in some from the neighbour- 

 hood of an ocellus near the two tentacles, and the conspicuous faintly-pinkish 

 manubrium (of a trumpet-shape) occasionally encloses a Copepod. Pro- 

 fessor Alex. Agassiz § connects it with a tubularian growing singly ; it 

 might also have been supposed to be related to Corymorpha, which occurs 

 off the Budda Rock. Another interesting addition to the pelagic fauna 

 is the beautiful garnet-tinted Halistemma, several examples of which were 

 procured in the bottom-net, and described by the Rev. A. D. Sloan, 

 B.Sc.|j 



The larval forms of Peachia and allied species occur with great regu- 

 larity in spring and summer — the earlier stages during the former period, 

 the older during the latter. 



Very few Radiolarians have been obtained in the surface-nets. On the 

 other hand, the various species of Ceratium are abundant almost through - 



* Ann. Nat. Hist., ser. 6, vol. 6, p. 174. 



+ I am indebted to Professor Jeffrey Bell for the identification of this form. 



X Quart. Jour. Mier. Sci., vol. 34, p. 105, Nov. 1892. 



§ N. Amer. Acalephce, p. 193, 1865. 



|| Ann. Nat. Hist., 1891, 6 ser. vol. 7, p. 413. 



