ON THE ZOOLOGICAL STATION AT NAPLES. 373 



The illness and period of convalescence lasted four weeks, and seriously 

 interrupted the course of my work, as I only remained at the Station for 

 little more than a fortnight after recovery. I left Naples on March 27. 



It had been ruy intention to work at the development of the Polychseta, 

 but the only suitable form available at that season of the year (a Nereis) 

 was already appropriated by one of the workers at the Station. Eggs of 

 Spio fuligiuosus and of Pobjmnia nebulosa were easily obtained in quantity ; 

 in both cases, however, minuteness and opacity deti-act from their value 

 for embryological research. 



I was able to confirm Salensky's account of the segmentation stages 

 in the egg of S. faliginosiis. I made unsuccessful attempts to fertilise 

 artificially the eggs of Arenicola mariiia, A. Grubei, and Lanice conch.ilega ; 

 the sexual products appeared to be unripe. The first fortnight was 

 occupied by these preliminary studies, and in examining the rich and 

 varied proceeds of the daily dredgings and tow-nettings. A fresh supply 

 of the wonderful pelagic life in the Bay was brought in every day with 

 very few exceptions, and I had many opportunities of examining numerous 

 forms of annelidan larvae in the living condition, and of preserving a large 

 quantity of material. Still there seemed to be little probability of 

 obtaining a sufficient number of specimens in different stages of the 

 development of any one form, and I therefore took up, at the kind 

 suggestion of Professor Eisig, the study of the adult anatomy of the 

 Chlorhaemida3, a family of polychcet worms. 



I received numerous specimens of Siphonostoma diploclicetos, Otto, and 

 of Trophonia plumosa, Clap. ; further, specimens of Stylarioides monilifer, 

 D. Ch., and of Stylarioides Edirardsii {=Lopliiocephala Edwardsii, 

 Costa). Sig. Lo Bianco kindly handed over to me a few specimens of a 

 Stylarioides new to science, which were found associated with Balano- 

 (jlossus on one occasion some years ago, and has not again been seen. I 

 also received alive a single specimen of each of two hitherto unknown 

 species of Trophonia. 



I have given most attention to S. diploclicetos, as this species is con- 

 venient for dissection, &c., and common. The worm is 6-7 cm. long, 

 has 40-50 segments, and is about 1 cm. across the widest part of the 

 body, a third of the total length from the anterior end. From this point 

 backwards the animal tapers gradually to the hinder end ; the anus is 

 terminal. More than half of the width of the animal is taken up by the 

 thick investment of a substance partly colloid and partly mucous. 

 Through this and the transparent epidermis the brightly coloured viscera 

 are sometimes very clearly visible. The soft sheath covers the whole of 

 the body behind the first pairs of setfe. It is secreted by mucus-cells 

 borne in the heads of clavate, filiform, epidermal papillse. The swollen 

 heads of the papilla) just reach the surface of the sheath, and a secretion 

 from them replaces a thin mucous outer layer which is periodically cast. 

 To this layer adheres a continuous coating of the ooze in which the 

 animal lives. The fresh external deposits of mucus are soluble in a 5 to 

 10 per cent, solution of sodium carbonate, and are insoluble in acids. 

 The older internal layers are not affected by the alkaline solution, and 

 have probably undergone some chemical change. They are distinctly 

 colloid. The papillae are longer and more numerous on the dorsal than 

 on the ventral surface, and there is a crowded group of long ones inter- 

 spersed with each bundle of set». These appear to be sensory, and bear 

 short sensory hairs at their tips. Below the mucous sheath lies a thin 



