354 DR. W. B. CARPENTER ON TOMOPTERIS ONISCIFORMIS. 



The first phase under which the Tomopteris presented itself to me is delineated in 

 Tib, LXII. fig. 1, under a power of 10 diameters. Its entire length was about -20 of an inch. 

 Its body was elongated, not quite cyUndrical, but somewhat flattened, and extremely trans- 

 parent ; there was no other segmentation than that which was marked by the projection 

 of the lateral appendages ; but a delicate transverse wrinkling became apparent when a 

 sufficient magnifjdng power was employed, as is indicated in figs. 2, 3, the former showing 

 the dorsal, and the latter the ventral surface, under a power of 38 diameters. The part 

 which may be designated as the head, from its containing the mouth, the nervous ganglia, 

 and the eye-spots, and from its bearing what seem to be the principal organs of feeling, 

 is not separated from the body by any constriction ; and the perivisceral cavity is not only 

 continued into it, but extends also into its appendages. These are of a very remarkable 

 nature. In front of the head there projects (figs. 2, 3) what might be regarded as a short 

 continuation of the body, narrowed into a kind of peduncle ; and this terminates anteriorly 

 in a pair of large horn-like appendages that project transversely on either side from their 

 common base, somewhat after the fashion of the horns of certain Ruminants. Between 

 the foregoing and the head, there arise from the under side of the peduncle a second pair 

 of these horn-like appendages, which are smaller than the first ; the inferior position of 

 these is seen in fig. 4, which gives a front view of the head and its appendages. The 

 perivisceral cavity is distinctly continued into the neck and the first pair of horns ; but I 

 could not satisfy myself that it penetrated into the second. From the sides of the head 

 itself there projected a far more remarkable pair of appendages, nearly half the length of 

 the body (fig. 1), which may for convenience be distinguished as the styliform. These 

 were supported at the base by a, lateral projection of the head on either side (figs. 2, 3), into 

 which the perivisceral cavity extended, and which also contained the muscular appa- 

 ratus that acted on the styliform appendage itself. This consisted of a long slender rod, 

 which, though obviously very firm in texture, was not inflexible, and which, therefore, I 

 should judge to be horny rather than calcareous. This rod was invested by a prolonged 

 membranous sac, toleralily wide at the base, but gradually narrowing towards the apex, 

 which appeared to close-in around the base of the rod, so that its cavity seemed com- 

 pletely isolated from the perivisceral cavity in which it lay ; and it was to each side of 

 this membranous envelope that the muscular bands were attached, which gave free 

 motion to the styliform appendage. 



The body bore ten pairs of lateral appendages, of which the third was the largest ; 

 the size of the 2nd being about the same as that of the 5th and 6th ; that of the 1st 

 about the same as that of the 7th ; and that of the 8th somewhat smaller ; whilst that 

 of the 9th was not above half that of the rest ; and the 10th (of whose character I was 

 not at fii'st by any means certain) was merely rudimentary. Each of these appendages 

 consisted at its base of a nearly cylindrical prolongation of the body, transversely wrinkled 

 like it, and containing an extension of the perivisceral cavity ; this basal portion gradu- 

 ally narrowed itself, and then underwent bifurcation into two lobes, each of which sup- 

 ported a flattened fin-like expansion of somewhat oval form. In this expansion a sort of 

 fibrous areolation could lie seen with a sufiicient magnifying power (figs. 2 a, 3 a). In 

 theii- usual position these two fins seemed to be nearly at right angles to each other ; 



