12-21 



The Laiicc'let attains in Scandinavia a length of 

 .ihiiiit ' , dm. LiLLJEBOiMj's lai'gcst specimens were 52 

 nnii. lung. According to ('aki's it sometimes mea- 

 sures at least 70 or even 100 mm.' During life the 

 body is of a jelly-like transj)ai-(Micy; thnjugii tiie skin 

 and muscles may b(! perceived the light gi'een notochord, 

 the somewhat darker c«cuni, and the; stomach with 

 intestine, th<' last-mentioned organs more or less dark 

 according tn (lie nature of their contents. In a certain 

 light the skin appears somewhat iridescent, and a hand- 

 some appearance, as of a row of white, transparent 

 rings, is presented by the plate-like rudimentary tin- 

 rays. Wluni the seminal or ovarial sacs are full, they 

 are |)erceivable (^n each side as a sei'ies of \vhite or 

 green globules, the green egg-sacs each with a dark dot. 



The habits of the Lancelet have been sketched 

 abo\e. Its breeding-time lasts throughout the summer; 

 but in wet and chilly weather it does n(jt S|)awn. 

 Thekl (jbtained at the beginning of July a large number 

 of specimens which were placed in the aquaria of Kris- 

 tineberg and laid eggs that developed normally. At 

 Haugesund in Norway Lill.iei50kg received at the be- 

 ginning of August specimens not yet (piite ripe. (!)n 

 the west coast of Fratice and in the Mediterranean the 

 Lancelet commences spawning in March. According to 

 Hatscuek, as well as Ray Lankestek and Willey, 

 who made their ob.sei'vations in the well-known lagoon 

 of l^jiitano, near Messina, the spawning always takes 

 jjlace in the evening, segmentation commencing between 

 7 and S p. m. At 11, say the latter writers, the 

 gastrula begins to develop, and at 1 a. iii. it is com- 

 plete. At >') a. m. it begins to revolve by cilia within 

 the egg-inembranc, and at 5 a. m. it already has two 

 jiairs of niyoc(Blomic pouches, when it bursts the egg- 

 membrane and becomes free-swimming. Thirty-six 

 hours after the commencement of segmentation the 

 (■u.bryo has actiuired a mouth and a rudimentary gill- 

 slit. Soon afterwards the anus opens, ;iiid the lai-val 

 period now begins. The larva^ swim both at the sur- 

 face, where Malm foiuid them off (jaso Island (Bohus- 

 l.-in), and dee])er down, at a depth of 1.5 — 20 fthms., 

 according to Ray Lankestek and Willey. Here they 

 ■ire found in countless myriads together with other 

 minute marine creatures {Xoctilucfe, Jieror, Sar/ittfe, 



(J(ilani) and their larva', amongst that mass (Hensen's 

 plankfoii) which the Norwegians call Aat''. The deve- 

 lopment of the larxa progresses much more slowly than 

 that of the (anbr\<i. A fortnight is said to elapse be- 

 fore the formation of the second gill-cleft; and the 

 remainder of the development, until the atrium is 

 com])lete, and the Lancelet begins to bury itself in 

 sand or mud, is said to take months (Hatschek). The 

 Course of the development is besides very irregular, 

 and it may be so protracted, at least in the North, 

 that Di-. ('. \\'. Armvii.Lius found larvae 5 mm. long 

 swinnuing freely at a depth of 1.5 — 30 m. below the 

 surface of (iullmar Fjord, in the middle; of November. 

 In its hiding-place at the bottom fht; Lancelet 

 leads the life of the worms, and to esca]je danger it 

 buries itself deejier down, for Malm remarks that, un- 

 less the dredge — the instrument most generally em- 

 ployed in the capture of marine animals at the bottom 

 — takes a sufficient hold in the gravel, sand, or nnul, 

 there is little hope, even in places known to be fi'e- 

 rpiented by the Lancelet, of .securing a single specimen. 

 Few fishes are so tenacious of life; and even if the 

 body be cut into pieces, the ciliary motion does not 

 cease at once in the severed parts. In salt water 

 changed from time to time, it may be kept alive for 

 months; and Lilljebokg relates that a number of Lan- 

 celets which he had dredged up at Haugesund on the 

 2nd of August, in a quantity of shellsand, and thrown 

 on the dry rock, were alive three days afterwards, 

 though the moisture of the sand was not very great, 

 and though rain had fallen in the interval. In spite 

 of the sluggish life it usually leads, the Lancelet is 

 quick (jf movement when disturbed, wriggling about 

 in the aquarium like a young Eel, but with either end 

 foremost. Its endurance is not great, however; if the 

 observer should desire to induce the captive to lie still 

 for examination, it may easily be tired out, and it 

 will then suffer itself without moi'c ado to be conveyed 

 where a closei- view may be obtained, provided only 

 that it has no soft bottom in which to hide itself. In 

 the day-time it lies motioidess. At night it moves 

 about; but if a light be brought near rhe aquarium, 

 it hastens to conceal itself. As human food it is worth- 

 less; but it has enemies, no doubt, in plenty. 



" Cakus, liowever, combines this species with the Pacific Bratichinstoma, and his account of Lancelets 1 ilni. long iiiny perhaps de 

 pend on that fact. 



* See above, pp. 970, 971. 



■• Bih. Vet. Akad. Handl., Bd 20, Afd. IV. No. ;i. p. 11. 



