152 EXOGONE GEMMIFERA. 



seventh segment (fourth bristled) and is whitish, with transverse rows of glands to the 

 number of about a dozen (Viguier). It has a rhomboidal outline or resembles a square with 

 the angles rounded. The stomach behind has two lateral cseca (the salivary glands of 

 Pagenstecher). On each side of the commencement of the proboscis is a brownish organ 

 placed opposite the first setigerous foot. 



The intestine is of a yellowish or brownish hue, and has a moniliform outline, and 

 oily granular matter in its glandular walls. 



The typical foot has a short and somewhat conical dorsal cirrus, and a ventral cirrus, 

 with the intermediate setigerous region. The latter, in the males and certain females, 

 has a tuft of long swimming-bristles between the dorsal cirrus and the setigerous region. 

 The superior ventral bristle is the strongest, with a curved shaft and a short terminal piece. 

 The next has a longer tapering terminal piece, then follow two with bifid terminal pieces 

 like those of Autolytus (though Viguier's figure is peculiar), and, lastly, a simple curved 

 bristle. The curvature of these inferior bristles resembles that of a gun-stock. 



The nine pairs of larvaB in the example from St. Andrews are flask-shaped, and with 

 a reddish-pink granular mass of yolk at the enlarged central portion, and have two 

 processes (caudal cirri) posteriorly at the attached end, and three at the anterior or free 

 end, viz. the median and lateral tentacles. They corresponded, therefore, with the stage 

 shown in Viguier's Plate IV, fig. 29, the French author having, under favourable oppor- 

 tunities, given an excellent original account of the escape of the ova, their attachment 

 to the region of the segmental aperture a little in front of the ventral cirrus, and their 

 subsequent development. 



In a female, procured between tide-marks at Lochmaddy, about a quarter of an 

 inch in length, pale — almost translucent — marked down the centre by a moniliform yellow 

 band from the intestine, twenty-one pairs of flask-shaped, rose-pink embryos with a red 

 spot in the centre occurred on the ventral surface. The head and nine segments only 

 were devoid of them in front, whilst posteriorly the embryos nearly reached the tip, 

 which may, however, have been broken. 



Viguier found the male with short swimming-bristles, and the perivisceral cavity 

 from the ninth or tenth normal segment to the posterior end— with the exception of the 

 tip of the tail — filled with sperms, the sexual region thus occupying about twenty 

 segments. The short swimming-bristles begin somewhat behind the first sexual 

 segment. The sperm-sacs (his seminal vesicles) appear to be fusiform and to stretcli 

 across each segment to open at the ventral pore on each side, a little behind the ventral 

 cirrus, at which point also a group of four bacillary corpuscles is found. 



In the female, Viguier found some with and some without the swimming-bristles, 

 which, as in the male, commenced at the first sexual segment, or a little behind it, and 

 continued to the ante-penultimate segment. The ova are developed under the intestine in 

 pairs in the ccelomic space of each segment, which they by-and-by fill. They have 

 externally the vitelline membrane and are extremely mobile, in short, almost amoeboid in 

 their nature, for when ripe they pass outwards, apparently by the segmental aperture. All 

 the ova are about the same stage in development, and appear to be fertilised after their 

 escape and attachment. Viguier figures the two-, four-, eight-celled, and the morula 

 stages, and also what he regards as invagination at a later stage, the aperture (mouth) 



