48 ANATOMY OP THE ENOPLA. 



transverse section {e.g., Plate X, fig. 10) of an animal which has been preserved with a 

 distended chamber ; then, indeed, it seems to be the chief cavity of the body. The presence of 

 the reproductive elements also has a considerable influence in modifying the size of the space, 

 which in the ripe animal is pressed upwards and towards the median line, while in the spawned 

 worm it expands freely in all directions. It is a mistake, however, to suppose, with M. de Quatre- 

 fages, that no chamber exists posteriorly in the ripe animal, for it holds the same anatomical 

 relations from the ganglia to the tail as at other seasons, only its calibre is encroached on poste- 

 riorly, and the consequent distention by the proboscis and fluid makes it more conspicuous in 

 front. The chamber is not continued throughout the body in long species, such as Nemertes Neesii 

 and N. gracilis, and is absent in the aberrant N. carcinopliila. 



In the foregoing cavity the proboscis floats in a clear fluid, apparently first noticed by Pallas, 

 rich in large flattened corpuscles, which possess a minutely granular appearance. In the living 

 animal these generally have a fusiform outline, from a slight enlargement in the middle (Plate X, 

 %• 15, b). They are also accompanied by certain globules and granules. The corpuscles vary 

 in size, and frequently adhere together in a dying animal, from the very coagulable nature of 

 the transparent fluid in which they float ; and occasionally fibrinous shreds may be observed 

 attached to them under the same circumstances. The fluid, indeed, is highly organized, and 

 very different from sea-water, to which Dr. T. Williams compares it. When the proboscis has 

 been gently protruded under chloroform, the corpuscles in the interspace may by-and-by be seen 

 grouping together, so as to form stellate bodies resembling miniature Solasters, spiked bodies like 

 thornapples, flattened structures with pectinate ends, and various other forms. In Tetrastemma 

 melanocephala the corpuscles are comparatively small, some being clear, spindle-shaped bodies, 

 others granular and rounded. The enormous increase of cells and granular masses in the pro- 

 boscidian fluid, after the rejection of a proboscis, is well seen in this species. In other 

 Tetrastemmce the corpuscles (Plate X, fig. 14), though similar in shape to those of A. lactifloreus, 

 are comparatively large ; and in a variety of T.flavida, which I am inclined to regard as the Folia 

 sanguirubra of M. cle Quatrefages, they are tinged pinkish or reddish by transmitted light (Plate 

 X, fig. 11). All are not similarly tinted, some being pale, others yellowish, while many are bright 

 red, the colour in each case being in the nucleus. Globular bodies and granules are present, 

 as in Amp/iiporus. The skin of this specimen contained many minute reddish pigment-specks, so 

 that to the naked eye it had a delicate salmon-pink appearance. "Reddish granular masses occa- 

 sionally occur in the proboscidian chamber of A. lactifloreus, and in various species of Tetrastemma, 

 generally associated with reddish specks in the skin, 1 and it is curious that a rejected proboscis 

 assumes the same hue by transmitted light. After extrusion into the water, the shape of the cor- 

 puscles soon alters, and they adhere together and become translucent. 



Amongst the authors who have alluded to the proboscidian chamber, Delle Chiaje and Grube 

 seem to have possessed a fair knowledge of its arrangement and structure. (Ersted, again, gives 

 a small figure of a transverse section of his Notospermus flaccidus, and characterizes the cavity as 

 "canalis in quo penis est," indicating by a blank beneath what is evidently the digestive tract. 

 He thus did not advance the physiology of the parts further than Huschke, who called the pro- 

 boscis a male organ, and the nerves semen-canals. His interpretation of structures, however, is 

 more distinct in his section explanatory of the Family Amphiporina, in which the digestive cavity 



1 In the reddish-brown Zetlandic variety of T. Candida the proboscidian chamber contains many 

 brownish-red pigment-masses. 



