269 Part I[T.—Seventeenth Annual Report 
in tow-net gatherings from the Clyde—the only Scottish locality where it 
has as yet been observed. The form referred to, which in general appear- 
ance is not very unlike the widely distributed crustacean known as 
Lucifer, has been known for a considerable period ; it was described 
and figured under the name of T'rachelifer, by the late Mr. George 
Brook in 1888*, but is evidently immature, and there is still 
some doubt as to the species to which it really belongs. The neck 
of this young form is long and slender; the thorax is small, and is 
furnished with wore or less rudimentary appendages; the slender 
abdomen is more than twice the length of the neck, and the last 
abdominal segment is as long as all the other segments of the abdomen 
put together; the telson and uropods are comparatively short, and more 
or less rudimentary. Figure 16, PL. XII. represents one of the Clyde 
specimens, which measured over all about 16°5 millemetres (2 of an inch). 
The specimens that have been observed vary in length to a small extent, 
but all possess the same slender Lucifer-like form. 
Habitat.—Station VII., Firth of Clyde. (I have also a specimen from 
Loch Fyne collected in 1886.) 
Additional Remarks.—Figures 17 to 20, Plate XII., exhibit on a some- 
what enlarged scale portions of the Lucifer-like crustacean referred to above. 
In fig. 17, which represents the front part of the cephalic segment, the eyes 
are large and somewhat divergent; the triangular rostrum is slightly shorter 
than the eyes; both pairs of antennz are slender and elongate; the 
antennal scales are also slender and rather shorter than the basal part of 
the antennules. Fig. 18 represents what appears to be one of the first 
perevpods. In the specimen dissected this was the only pair that 
had the extremities of the principal branches chelate ; all the other trunk 
legs appear to be simple. Fig. 19 represents one of the first pair of 
abdominal appendages, which are all more or less rudimentary; each 
appendage consists of a single unjointed branch, with a furcated 
extremity. Fig. 20 represents the posterior end of the last abdominal 
segment, together with the uropods and telson; the appendages of the 
last abdominal segment form tapering and slightly curved processes; the 
uropods are foliaceous, and little more than half the length of the telson ; 
the telson is comparatively of large size. In the specimen dissected for 
drawing, the telson was somewhat imperfect. The extremity is therefore 
indicated by dotted lines, but in another specimen in which the telson 
was fairly perfect the following characters were observed :—The terminal 
lateral processes had each two small teeth on the inner margin, and the 
part between the lateral processes was furnished with twenty-two short 
and slender marginal spines; the two middle spines were rather shorter 
than the others ; and there was a slight but perceptible gradation in the 
length of those on each side of the two central ones, the spines nearer 
the centre being somewhat shorter than those more distant. The larva 
above referred to was described by Claus as eine in vieler Hinsicht merk- 
wiirdigen Larve ina paper Zur Kenntniss der Kreislaufsorgane der Schizo- 
poden und Decapoden, in Arb. d. z. Inst. Univ. Wien. V. 1884, p. 302 
(32), Pl. VIIL, figs. 48-50. The same writer subsequently described a 
somewhat more advanced specimen as the larva of Calliaxis adriatica, 
Heller, ibid. VI. 1886, p. 63, Pl. V., fig. 45. The identity of Brook’s 
Trachelifer with Claus’s Calliaxis—larva is pointed out by Korschelt 
and Heider, Lehrb. d. vergl. Entwicklunysgesch. d. wirbell. Th., L, 
p- 471. Calliaxis is not yet known as a British form, being only known 
from the Adriatic and from Naples: at the latter station the larva is met 
with in the surface-fauna, but the adult has only been found once in 25 
years (S. Lo Bianco, Mitth. Zool. Stat. Neapel. XIII, p. 503, 1899). 
