of the Fishery Board for Scotland. 243 



in it an account of the male as well as of the female. In my previous 

 record of the species I stated that one of the peculiarities of Botryllophilus 

 was " the almost constant existence of a single ovigerous sac of a strictly 

 spherical form sheltered between the fifth feet." I now find that this sac 

 in the specimens observed, both in the Clyde and the Moray Firths, is 

 really composed of two sacs, partly adherent to each other and so closely 

 joined as to appear as if they formed but a single globular mass. 



Description of the female. — Length of the specimen figured, 1*16 mm. 

 (about -jig- of an inch). The cephalothorax, which terminates anteriorly in 

 a short bluntly rounded rostrum, is somewhat narrow in front, but 

 becomes gradually dilated towards the posterior end and especially on the 

 dorsal aspect. Scarcely any trace of segmentation can be made out in 

 the cephalothoracic region, but this is probably due to the fact that the 

 Botryllus in which the specimen was obtained had been for several years 

 (since 1896) preserved in alcohol. The abdomen is narrow and elongated, 

 but is rather shorter than the cephalothorax (fig. 15). 



The antennules are very short and composed of four joints, the first is 

 considerably dilated, the second is moderately stout but much smaller 

 than the first ; the third and fourth are small ; the antennules are 

 furnished with a number of long and moderately stout setae, which appear 

 to be devoid of feathering (fig. 17). 



The antennae, which are two-jointed, are comparatively long and slender 

 and of nearly equal thickness throughout, they are each composed of two 

 (or (T) three) joints; the end joint is provided with three stout spines on its 

 inner margin, and a few spines and setae at the apex, the other joints 

 appear to be unarmed (fig. 18). The antennae are not provided with 

 secondary branches. 



The mandibles and maxillae appear to be obsolete or very rudimentary. 



The first maxillipedes are small and feeble, they are each composed of 

 three joints, the second and third joints are sub-equal and rather smaller 

 than the first ; the first joint is unarmed, the second bears two or three 

 spine-like setae on its inner aspect, and the third is provided with a few 

 terminal setae of unequal lengths, the outermost being considerably longer 

 than any of the others (fig. 19). 



The second maxillipedes are short but somewhat robust, the basal joint 

 is moderately distended, and larger than the second one, the third joint 

 is very small, the end-joint is narrow and fully twice the length of the 

 third and bears a short but strong terminal claw (fig. 20). 



The thoracic feet. — All the thoracic feet, with the exception of the fifth 

 pair, are short and robust and composed of two branches. In the first 

 and second pairs, the inner branches are very short and two-jointed ; 

 about eight plumose setae of moderate length spring from the rounded 

 apex of the second joint, and one from the inner margin of the first joint. 

 The outer branches, which appear to be uniarticulate, are rather longer 

 than the inner ones and are armed with a few small marginal and apical 

 spines, as shown in the drawing (fig. 21). In the third and fourth pairs 

 the outer as well as the inner branches are two-jointed ; the inner branches, 

 which are somewhat alike in both pairs, are rather longer than those of 

 the first pair, but their armature is somewhat similar, except that the end- 

 joints bear six instead of eight plumose setae ; the outer branches of the 

 third pair are somewhat similar to those of the first except that there is 

 an articulation between the two proximal marginal spines, dividing the 

 branches into two joints (fig. 22) ; the outer branches of the fourth pair 

 are less robust than the inner branches, but are nearly equal to them in 

 length ; a single small seta springs from near the end of the outer margin 

 of the first joint, while the second is furnished with four apical and sub- 



