18 Prof. M'Intosh's Notes from the 



{medusae, Savigny), is a southern one from the shores of 

 Devon and neighbouriuj^ areas. 



The cephalic lobe presents a small and inconspicuous 

 dorsal collar, which at each side bends down to disappear in 

 the general plate, and without joining the supra-oral arch, 

 Avhich is fan-shaped and projects little. The space between 

 tlie latter and the cephalic collar is occupied by the grooved 

 tentacles. From the outer border of the cephalic region 

 a large lamella arises and passes with a slight median 

 excavation entirelj^ across to the other side — forming thus 

 a great post-oral platform. A differentiation on each side 

 occurs in the form of a curved line, which extends from 

 the segment-junction ])Osteriorly obliquely forward and 

 outward, thus marking off a central and more flexible region 

 and two stiffer lateral regions. The great development of 

 this post-oral flap is characteristic of the species. 



The body has the typical Terebellid outline — enlarged in 

 front, and tapering gradually to the posterior end^ at which 

 is the terminal anus. It is rounded dorsally, flattened 

 ventrally in front and slightly so posteriorly. 



The segment succeeding that bearing the post-oral lamella 

 carries the first pair of branchiae, but is not distinguishable, in 

 the sole example available, from the next segment either 

 darsally or ventrally, though it may represent in the dorsal 

 region part of the segment in front. 



The following segment, carrying the second pair of gills, 

 has a broad fan-shaped flap at each side about midway 

 between the gill and the ventral scute ; whilst the following, 

 or fourth, segment bears the third branchia and the first 

 bristle-bundle. The ventral scutes in the example are not 

 separated by the deep furrows so characteristic in other 

 forms, but appear to be nearly continuous from the anterior 

 broad scute to the narrow median ridge about the eleventh 

 bristle-tuft. All the segments are marked by narrow 

 rings. 



The branchite ai'e comparatively small, distinctly sepa- 

 rated, and with short stems, the usual gradation occurring 

 i'rom the first to the third. They are distinguished from all 

 the others by their very finely-branched terminal divisions. 

 The main stem and its subdivisions are short, so that the 

 entire organ in each case projects proportionally little. It 

 is dichotomously divided. The branchiae of the Mediter- 

 ranean so-called L. medusoi, though also furnished with fine 

 terminal ramuscles, are more lax in branching, the separate 

 divisions being longer. 



Seventeen pairs of prominent setigerous processes occur 



