U2 



Sidefladerne af Hovedet (se Tab. XV, Fig. 1), og 

 hestaar hver af et cylindriskt, miiskTilost Skaft og 

 2 stærkt forlængede Grene. Skaftet viser ved Basis 

 en noget albnformig Boining og er lier i Bagkanten 

 forsynet med et lidet borstebesat Fremspring (se 

 ogsaa Fig. 3, a'''). Dets ydre Del er meget boielig 

 og delt i omtrent 8 korte Segmenter tæt besatte 

 fortil med stærke, pigformige Borster. Grenene er 

 meget smale og af meget betydelig Længde, navnlig 

 den indre eller bagre, der er over dobbelt saa lang 

 som Skaftet. Begge Grene er delte i talrige (fra 

 lU til 14), meget skarpt afsatte og noget skivefor- 

 mige Led, livoraf hvert i Bagkanten har Uere lange, 

 2-leddede og fint cilierede Svommeborster, i Forkan- 

 ten ligeledes et større Antal af stærke, i Enden 

 noget hageformigt krummede Pigge. Saavel Grene- 

 ]ies indbyi-des Længde som Antallet af Led paa hver 

 (Tren er forovrigt noget varierende hos forskjellige 

 Individer. 



Overlæben (Tab. XV, Fig. 2, 4, L, Fig. 7) nd- 

 gaar bagtil som den i;middelbare Fortsættelse af 

 Hovedets ventrale Del, og hvælver sig paa Under- 

 siden nd over Kindbakkernes Tyggedel, samt naar 

 med Spidsen ind mellem Basis af Iste Podpar (se 

 Fig, 1). Den er imidlertid til en vi.s Grad bevæge- 

 lig, idet den ved to tynde til dens Basis lobende 

 Muskler kan loftes noget af fra Munddelen og igjen 

 ved andre Muskler i)resses tæt ind mod samme Af 

 Form er den næsten halveylindrisk, med den nedad- 

 vendte Flade stærkt convex, den ovre noget eoncav. 

 Ved Enden indsnævres den pludselig, dannende til 

 hver Side et vinkelformigt Hjorne, og forlænger sig 

 til en meget boielig og i Enden tint cilieret Spids. 

 Oveiiover denne tentakelformige Fortsats har den 

 en skiveformig, lodret stillet Endelamelle, der læg- 

 ger sig ind mellem de 2 Par Kjæver, naar Over- 

 læben presses ind mod Legemet. I Overlæbens indre 

 sees flere celleagtige Legemer, der .synes at være 

 af kjertelagtig Natur, og ligeledes et storre Antal 

 tværgaaende Muskler, der virker paa den blode ovre 

 Flade og rimeligvis har Betydning ved Svælgnings- 

 processen. 



Kindbakkerne (Tab. XV, Fig. 2, 3, 4, M, Fig. 8), 

 der som 2 Boiler omfatter Siderne af Legemet paa 

 (irændsen mellem Hovedet og Nakkesegmentet, er 

 meget kraftigt udviklede og hos det voxne Dyr uden 

 ethvert S])or af Palpe. Den spidst udlobende ovre 

 Ende af det baadformige Corpus er bevægeligt arti- 

 culerct med en liili'ii knopformig Fortykkelse af 

 Integumeutet ved hver Ende af den Tværsutur, som 

 Hndes i l>unden af den dorsale Indbugtning mellem 

 Hovedet og Xakke.segmentet. Tyggedelen er sta'rkt 

 indboiet og sondret fra (Jorpus ved en tydelig Ind- 

 knibning eller Hals. Den ender, s(jm lins Branclii- 

 pddidei'iie med en bred, lint rillet Tyggelhidi' iiden 



from the lateral surfaces of tln^ head, with a broad 

 base (see Pl. XV, fig. 1), and each consist of a 

 cylindrical, muscular scape, and two greatly elon- 

 gated rami. The scape exhibits at the base a some- 

 what elbow-like bend, and on the hind margin at 

 this point, is furnished with a little setous projec- 

 tion (see also fig. 3, a'''). Its distal part is very 

 flexible, and divided into aliout 8 short segments, 

 thickly clothed in front with strong spiniform brist- 

 les. The rami are very narrow, and of considerable 

 length, notably the inner or hinder one, which is 

 more than twice as long as the scape. Both rami 

 are divided into numerous (from 10 to 14) very 

 clearly defined and somewhat lamellar joints, each 

 of which has several long, bi-articulated and finely 

 ciliated natatory bristles in the liind margin, and a 

 large number of strong, rather hamous spines in 

 the front margin. Both the mutual length of the 

 rami, and the number of joints in each ramus, varies 

 somewhat in dirterent specimens. 



The labrum (PI. XV, figs. 2,4, i, fig. 7) projects 

 liackwards as the immediate continuation of the 

 ventral part of the head, and on its inferior side 

 arches over the masticatory part of the mandibles, 

 its point extending in between the base of the first 

 pair of legs (see fig. I). To a certain extent, how- 

 ever, it is movable, for it can be raised a little 

 from the oral parts by two thin muscles running to 

 its base, and again, by other muscles, can lie pressed 

 close in against those parts. In shape, it is almost 

 semi-cylindrical, with the downi-turned surface very 

 convex. At the extremity it is suddenly contracted, 

 forming on each side a sharp corner, and being- 

 produced to a very flexible point, finely ciliated at 

 the extremity. Above this tentacular projection 

 there is a discoid, verticallj'-situated, terminal 

 lamella, which is interposed between the 2 pairs of 

 maxillæ, when the labrum is pressed in towards 

 the bod^'. In the interior of the labrum are visible 

 several cell-like bodies, which appear to be of a 

 glandulous nature, and also a large number of 

 transverse muscles, which act upon the soft upper 

 surface, and jirobably ]ierform a part in the process 

 of swallowing. 



The mandibles (PI. XV, figs. 2, 3, 4, J/, fig. 8) 

 which embrace the sides of the body like 2 bows, 

 on the boandary-line between the head and the cer- 

 vical segment, are very powerfully developed, and, 

 in the full-grown animal, without a trace of jialpi. 

 The pointed upper end of the boat-like body is 

 movably articulated with a small l)nd-like thickening 

 of the integ^iment at each end of the transverse 

 suture found at the bottom of the dorsal hollow 

 between the head and the cervical segment. The 

 masticatory part is very much incurved, and sejia- 

 rated from the corjius by a distinct constriction or 

 neck-. It ends, as in the Branchiiiodida' with a 



