ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 709 



are seen to take part. The upper pectoral fin is erected sharply and 

 spread .out, and is not employed as a motor fin. It thus forms a motionless 

 black flag, held up conspicuously, like that of the weever, and with 

 exactly the same menacing attitude. The following considerations are 

 urged in support of the hypothesis. 1. That the geographical distribu- 

 tion of Solea vulgaris and its nearest allies is closely similar to, if not 

 identical with, that of the two common species of Trachinus. 2. That 

 the sand-loving and sand-hiding habits of the two forms are closelv 

 similar, and that they actually inhabit the same grounds, the young 

 soles with T. uipera, and the adults in deep water with T. draco. 3. 

 That on disturbance each type holds its black fin erect in a menacing 

 manner ; that of the sole is held at right angles to the normal position 

 for the Pleuronectidas. 4. That the pectoral fin of other Pleuronectidse, 

 or even Soleidas, is not coloured black, and is not held erect in the same 

 maimer. 



Production of Sound in Drum-fishes.* — R. W. Tower gives an 

 account of a series of experiments undertaken with a view to determining 

 the cause of the production of sound in the drum-fishes (Sciasnidas), in 

 the sea-robin (Prionotus carol inns), and the toad-fish (Opsanus tan). 

 The structure of the swim-bladder in these forms is described and 

 figured, and an account is given of hitherto recorded observations and 

 theories on the subject. The experiments show that the scianoid fishes 

 which make a drumming noise have specific sound-producing muscles, 

 which are only superficially attached to the swim-bladder. For this 

 drumming-muscle the name of " musculus sonificus " has been proposed 

 and adopted. The chief cause of the drumming noise is the contraction 

 of the musculus sonificus, which produces a vibration of the abdominal 

 walls and organs, especially of the swim-bladder. 



The sea-robin and the toad-fish, which make a " grunting " noise, 

 have muscles which are intrinsically connected with the swim-bladder, 

 and are known as intrinsic muscles. The noise is caused by a contrac- 

 tion of these muscles, which produce a vibration in the walls of the 

 air-bladder. The mechanism in the Sciaenidas is adapted to the pro- 

 duction of rapidly repeated sounds. That in the sea-robin and toad-fish 

 is adapted to the production of sounds at more or less long intervals. 



Tunicata. 



California^ Ascidians.| — W. E. Ritter gives an account of the 

 Ascidians collected by the ' Albatross ' off the Calif ornian coast. He 

 deals with fourteen species, twelve of which are new. The new genus 

 Halomolgala has a test beset with processes containing calcareous 

 spicules ; the new genus Bmthascidia is long and pedunculate, with a 

 non-closable branchial orifice, with a very delicate branchial membrane 

 without true stigmata- 



's* 



Winter-buds of Clavellina Lepadiformis.J — H. Kert gives a 

 detailed account of the formation, structure, and history of the winter- 



* Ann. New York Acad. Sci., xviii. (1908) pp. 149-80 (3 pis. and 5 figs.). 

 t Univ. California Publications, Zoology, iv. (1907) No. 1, pp. 1-52 (3 pis.). 

 X Arch. Mikr. Anat., lxxii. (1908) pp. 386-414(1 pi.). 



