Nhadbe 
Vine ay 
Py 4 
| ~ of the Fishery Bourd for Scotland. 259 
a cephalo-thorax and abdomen closely beset with minute papille, of 
___-which fig. 18 is an enlarged representation. 
Male.—Body similar to that of the female but smaller (1°3 mm.). 
Anterior antenn eight-jointed ; the proportional length of the joints are 
as in the formula 
MO” O18 Bat ONE Bae a 
gS Ie Ee ae pom egy cas! 
distinctly hinged between the sixth and seventh joints, and indistinctly 
between the third and fourth. The fifth joint, which is very short, bears 
a long olfactory filament. The posterior antenne, mouth organs, and 
first pair of swimming feet as in the female. The last joint of the outer 
branches of the second pair of swimming feet bears at nearly right angles 
a long curved appendage closely resembling the blade of a reaping-hook, 
and setose on the inner margin (fig. 13). The basal joint of the inner 
branches of the third pair is furnished internally with a long slender pro- 
cess, which extends beyond the extremity of the branch, and is armed on 
the inner margin near the distal end with two barb-like teeth. The fourth 
and fifth pairs as in the female, except that the fifth is rather smaller and 
furnished with fewer setze. The abdomen five-jointed ; the posterior mar- 
gin of the first abdominal segment bears a foliaceous appendage armed 
with one long and two short, stout seta. Caudal stylets and setz as in 
the female. 
Habitat.—Off St Monans, Firth of Forth, in 14 to 15 fathoms water ; 
bottom clean course sand. Not uncommon. 
This interesting Copepod, which was described by Professor Brady in 
his monograph of the British Copepoda in 1880, is apparently local in its 
distribution, and is probably rare as well as local. The generic and 
specific descriptions given in the monograph were prepared from the 
examination of one specimen only—a female—and, as pointed out by 
Professor Brady, both descriptions were necessarily somewhat incomplete. 
Having some time ago in a single haul with the dredge secured a con- 
siderable number of spécimens including both males and females, the 
opportunity was taken advantage of to make a careful examination of 
both sexes so as to gain some knowledge of the affinities of the species. 
In the monograph alluded to Cylindropsyllus was provisionally placed 
among the Pecilostoma because of its apparently close relationship to 
that group, but as the structure of some of the mouth organs had not 
been satisfactorily made out no distinct place in the classification was 
assigned to it. 
By the careful dissection of a number of specimens I have been able, 
with the assistance of my son, to prepare a fairly complete description, 
with a set of drawings, of the more important and characteristic append- 
ages that distinguish Cylindropsyllus levis from other Copepoda. It will 
be observed by referring to the description and drawings that there are 
one or two characters which render the position of Cylindropsyllus among 
the Pecilostoma untenable. These are the distinctly hinged male anterior 
antenne, the presence of a secondary branch on the posterior antenna, 
and the form of the mandibles,—characters which indicate a closer 
affinity with the Harpacticide than with either the Pwcilostoma or the 
Siphonostoma. If, on the other hand, the appendages of the peculiar 
organ described as situated anterior to the mandibles be sucking disks, 
the position of Cylindropsyllus in the classification would be somewhat 
anomalous, as these appendages would indicate a tendency towards para- 
sitism in this Copepod,—a tendency suggested by Dr Brady. No indication 
of parasitical habits has, however, been observed hitherto in any of the 
Specimens obtained. 
