﻿PYCNOGOXIDA. 2" 



of its own, seven g-lands on each side of the animal, fig. 17 a. a. Of Pall. Iiaslala I ha\-e two fignres, pi. I, 

 fig. 18 — 19, which show a more advanced stage, the third pair of and)nlator\- legs being here already 

 ver\- much lengthened, so that all three pairs seem to ha\x- been de\-eloped at the same time; from 

 the first figure, howe\-er, it is distiuctlx' seen, that there must have been an inter\-al between the 

 second and third pair. In the species of Psnidopallciic the delay of the third pair of ambulatory legs, 

 is, however, much more considerable, as is already- shown b\- the two figures of I^scjidop. spiniprs., 

 pi. I, fig. 8 — 9. As to the further de\elopment I shall refer to the figures of Psnidop. circularise pl- I, 

 fig. 10 — 14. In the two first of these figures the development has not gone farther than to the re- 

 presentation of Psnidop. spii/ipcs, gi\'eu in the preceding figure, but in fig. 12 it has gone much farther. 

 Here the two foremost pairs of ambulatory legs have been fully de\-eloped (of the four uniform legs 

 only the foremost right leg has been drawn), while the leg of the third pair is still onl\' a bag-shaped 

 process with a characteristic stiff bristle implanted on the upper side, a little before the point. In the 

 same figure is furthermore seen the processes of the intestinal canal into the three j^airs of legs, 

 going in the wholh- drawn foremost leg quite into the outermost joint. No traces of embryonal legs 

 are seen, but neither, what is to be emphasized, is the least beginning of the imaginal fore limbs to 

 be found. In the fore edge of the first abdominal ganglion, or the suboesophageal ganglion are seen 

 through the epidermis a pair of short processes, as also a pair of still smaller, ballshaped appendages 

 farther back, inside the side margin; but no nervous fibres are seen to arise from these processes and 

 appendages. The anus is now distincth- open. Fig. 13 represents the same larva from the upper side, 

 but with the two forenu-^st j^airs of ambulatory legs completely removed; the oculiferous tubercle with 

 the eyes is distinctly seen. Fig. 14 gi\-es the last jjhase of the same stage. Here also the third pair 

 of ambulator)' legs ha\-e been almost fully developed, only the last joint but one wanting; but still 

 the lower side of the first segment of the trunk is as naked as in the preceding phase, fig. 12. 



Kroyer, in his second essay, Bidr. til Kundsk. om Pycuog. (1844), has given a description of 

 what he calls the first and second stages of Pal/cue iiitcniicdia (= PsciidopaUciic circiilari.<;)\ but the 

 description itself, and still more the figures in Gainiard's work of tra\'el (1849) P'-39' fig- 2 a. a. — d., of 

 which figures Kro\'er, no doubt, has been thinking, show distinctly that we here ha\e two phases 

 of the same lar\al stage, i.e. of the second stage, of which Kro\'er treats, and the figures given by 

 Kro\-er of the animals, fig. 2, a. and c. are completely answering to my figures 8 and 12 — 13, only 

 that in the first of my figures I have also the byssus-thread, and in the last one also the eyes. Tlie 

 omission of the e^-es may, I think, be due to the bad preservation of the larva whereb)' the elements 

 of sight have been remo\'ed from their position on the oculiferous tubercle; at least I believe to have 

 found these elements strewn round in the trunk of the original piece of Kroxer which 1 have had 

 occasion for examining, as well as the fresh specimen drawn here. Otherwise I think it to be the 

 real or apparent want of genuine end)r\onal legs, and the contemporaneous de\elo])menl of the two 

 foremost pairs of andjulatory legs, b\- which these latter get a certain resemblance to the former limbs, 

 which has induced Krox'cr not onh' to suppose this degree of the second lar\-al stage to be the 

 first, but also, what is much worse, led him to the wrong supposition of the real embryonal legs 

 de\elo])iug into the two foremost ])airs of andjulatory legs. But this same mistake, on the other 

 hand, has freed Kroyer from the prt-sent conunou wrong interpretation of the inuiginal fore limbs 



