126 Prof. M'Intosh's Notes from the 



The differences in the muscular and other tissues of the 

 anterior and posterior regions sufficiently explain the fact 

 that, as a rule, only the anterior region is tossed on shore 

 by storms. 



In the first segment of the second region, and in the 

 following six to eleven, are the openings for the issue of the 

 genital elements on papillae on the ventral surface. 



The second species, Capitella capitata^ Fabr., has a similar 

 distribution round the British shores to the foregoing, and 

 is likewise almost cosmopolitan. Its length is from 3-5 

 inches, and the anterior region has nine or ten segments. 

 The head is an elongated cone with two minute lateral 

 papillae (nuchal organs). The mouth opens as a puckered 

 orifice on the ventral surface of the peristomial segment. 

 Tlie body increases in breadth from the snout backward to the 

 sixth or seventh, and then slightly diminishes to the four- 

 teenth, behind which the body is somewhat narrower, though 

 this distinction is often obliterated. It diminishes posteriorly 

 and ends in a button-shaped process often with a dimple in 

 the centre ; but reproduction of this region is so common 

 that it is seldom a complete example is procured. The body 

 is rounded anteriorly, and when preserved has a tendency to 

 a quadrangular condition posteriorly, the ventral surface 

 being flattened and generally grooved anteriorly, the groove 

 in the larger examples being specially marked at the eighth 

 and ninth segments. On the lateral region of the body at the 

 junction of the seventh bristled segment with that following 

 in tlie female is a vertically elongated papilla with a deep 

 fissure (genital opening) in its centre. On the ventral 

 surface of the ninth bristled segment is the depression at the 

 end of the furrow leading into the aperture. 



The copulatory apparatus in the male (ninth and tenth 

 segments) has four bundles of strong spines — a pair to each 

 segment. About the middle of the ninth segment, and 

 apparently immediately in front of the papilla, is the anterior 

 series of ten spines, five on each side, the outer being the 

 smaller. The concavity of the curve of each spine, like the 

 point of the hook at its tip, is directed outward and backward, 

 the convexity looking toward the convexity of the adjoining- 

 series. A space occurs between them and the jjosterior pair, 

 the points of which are directed forward, and just appear, 

 under pressure, at the edge of the ciliated sexual aperture. 

 These spines are four in number, the two inner being larger 

 than the outer, and they are directed forward and inward. 



The anterior region (behind the peristomium) consists of 



