r\(. NOGONIDA 



pallene, and Pallene. In the last-mentioned genus, however, 



I have in / found, in stead of .1 single thread originating from the common gland, .1 



bum tliei short, somewhat curled threads each issuing from an excretorj duct of its 



6 and 17. I have seen no gland from which anj of these threads might arise; but I 



think it ile, in comparison with what Hoek has found in Nymphon hamatum, what I shall 



to, that each of the seven threads arises from a cell of its own. In Phoxichilidium 



Him I have found no trace of these glands, nor of their thorns and threads; the threads drawn 



on ■ the outermost joints of the embryonal legs, which arc prolonged in a bristlelike 



manner, and probably replace the wanting by ssus- threads; this larva, with its parasitic way of living, 



has n>> use tor the hook-, to which in the other Pycnogonida the- outermost joint of the embryonal 



i ha- been transformed. In Paranymphon spinosum 1 ), pL II, fi.14. -'^ -'(, I have found indistinct 



land and excretory duct, and the thorns were long and closed. In Zetes hispidus, pL II, 



: have found a distinct gland, but no excretory duct from it, and also here the thorns were 



d. It may be possible that in the two last-mentioned cases a reduction of a commonly occurring 



• ike n place, as it would seem to be natural in Phoxichilidium\ but it may also be supposed 

 that we have here a stage of transition from a simpler organ to the more perfect byssus-gland. 



Dohrn and Hoek have already earlier described and drawn this gland, and Dohrn espe- 

 cially, in Bau n. Entwick. Arthrop. 1870, has from the larva in the first stage of Achelia Icevis \ 

 Ammothea lav r) TatV, fig. 7, given a figure of the gland with its excretory duct and a secretion- 

 thread (byssus) projecting from the long, pointed, hollow thorn, but from Pycnogonum littorale in a 

 similar stage only the hollow thorn, he, as it would appear, not having seen the thread, not to speak 

 the gland. In the text he, when speaking of Achelia Icevis, describes the gland rather copiously, 

 but says nothing of its use or importance, I.e. p. 141 seq. Hoek. in Report Pycnog. Challenger , 



• this gland in Nymphon brevicollum and .V. longicoxa, pi. XX, fig. 2 and 5, and names it 

 in the explanation to the plates Spinning apparatus in the mandible . In another Nymphon, X. 

 hamatum, pi. XX, fig. 3 and ; he draws, instead of tin common gland, a whole heap of single miliary 



ad cells each cell with its own secretion-thread. No doubt this last form of glands with its threads 

 nds to the bundles of threads I have mentioned in Pallene brevirostris; and as in the last- 

 mentioned species the gland was different in structure from that of the other species of the s.nn 



r.irly related genera, so is also the structure of the gland in Nymphon hamatum peculiar, compared 

 with that in all the main species of Nymphon, from which the gland is known. Hoek in his text. 

 I.e. p. 141, compares the secretion-threads to tin- byssus-threads of the Lamellibranchiata, which coin- 

 I have found so appropriate that I have given to the gland itself the name of byssus-gland . 

 Dohrn generally draws thi -gland of the larvae of which he gives figures, but he does not 



always indicate it by special letters; when he does so, he gives the letters ///', which in the explan- 



1 the pla I .:- Hautdriiseu , and /'///>, which are rendered as Ausfuhrungs- 



Hautdrusen . In the text they are mentioned in the section entitled, Geschlechtsorgant 



dly on p. 7" seq., and here Barana arenicola is also pronounced destitute 



