60 



afsnit som lios Branchinecta, skjøndt deres indbyr- 

 des Længdeforhold er temmelig forskjelligt. 



Hovedet er forholdsvis af ringe Størrelse og 

 stumpt afrundet fertil. Det afgrændser sig skarpt 

 fra Xakkesegmentet, der til hver Side viser Skal- 

 kjertelen meget tydeligt. Trunciis er stærkt for- 

 længet, regelmæssigt cylindrisk, og delt i ikke min- 

 dre end 19 vel begrændsede Segmenter, hvert bæ- 

 rende et Par Branchialfodder. 



Bagkroppen udmærker sig i hoi Grad ved sin 

 korte og plumpe Form, idet den nejjpe indtager 

 mere end '/s af Kropslængden. Kjonsringene er 

 fuldstændig sammensmeltede saavel indbyrdes som 

 med den bagenfor liggende Del af Halen, paa hvil- 

 ken alene det bagerste Segment er tydeligt be- 

 grændset. Hele dette Parti har, seet ovenfra (Fig. 

 2), en næsten pæredannet Form, idet det fortil er 

 stærkt fortykket og ligesom opblæst, med en afrun- 

 det knudeformig Protiiberans til hver Side, medens 

 det bagtil gradvis afsmalnes. Breden over den for- 

 reste Del af dette Afsnit er mere end dobbelt saa 

 stor som Breden over selve Truncus. Sees Dyret 

 fra Siden (Fig. 1), viser sig Størsteparten af den 

 ventrale Side af dette Parti optaget af den voliimi- 

 nøse Ægbeholder, hvis forreste Del er særdeles 

 stærkt hvælvet, medens den bagtil kun rager ube- 

 tydeligt frem i Form af et kort koniskt Frem- 

 spring. Paa Enden af dette Fremspring findes den 

 ydre Aabning for Ægbeholderen, som hos Branchi- 

 necta, begræhdset af 2 vertikale mod hinanden be- 

 vægelige Læber, hvoraf den overste er den største 

 og ender i en tilspidset Knude (se Tab. X, Fig. 12). 

 Halepladerne (se Tab. IX, Fig. 6) er forholdsvis 

 korte, neppe mere end dobbelt saa lange som de er 

 brede ved Basis, og viser en bredt lancetdannet 

 Form, med Spidsen smalt afrundet. De er hver 

 kantede med omtrent 19 cilierede Børster der suc- 

 cessivt tiltager i Længde mod Spidsen. 



Øinene (Tab. X, Fig. ], o) er forholdsvis korte 

 og tykke, ne^jpe længere end Hovedets halve Brede, 

 og af den sædvanlige pæredannede Form, med Øie- 

 globen jævnt afrundet. Øiepigmentet er mørkt, dog 

 hos det levende Dyr med et tydeligt purpurrødt 

 Skjær, og de enkelte Synselementer vel udviklede. 

 Det enkle Øie sees som en tydelig mork Plet i Mid- 

 ten af Hovedets Pandedel. 



Første Par Følere (Fig. 1, a', Fig. 3) er for- 

 holdsvis betydelig kortere end hos Branchinecta, 

 neppe halvt saa lange som Øinene, men viser for- 

 øvrigt en meget lignende Bygning, og bærer paa 

 Spidsen de sædvanlige LugtepapiUer og Folebørster. 



Andet Par Folere (Fig. 1, a^) er ligeledes min- 

 dre eiul hos Branchinecta, og har Formen af 2, som 

 det synes, fuldkommen ubevægelige trekantede Flige, 



same body-divisions can be distingiiished as in Bran- 

 chinecta, although their mutual relations as to length 

 are rather different. 



The head is comparatively small and bluntly 

 rounded in front. It is sharply defined from the 

 cervical segment, which shows the shell-gland on 

 each side very distinctly. The trunk is greatly 

 elongated, regularly cjdindrical, and divided into no 

 less than 19 well-defined segments, each bearing a 

 pair of branchial legs. 



The posterior part of the body is highly remar- 

 kable for its short and stout form, constituting, as 

 it does, scarcely '/s of the length of the body. The 

 genital segments are completely coalesced, both 

 mutually and with that pai't of the tail posterior 

 to them, in which only the hindmost segment is 

 distinctly defined. The whole of this part, seen 

 from above (fig. 2), is almost pyriform, being very 

 much thickened in front, and as it were inflated, 

 with a rounded, nodiform protuberance on each side, 

 while posteriorly it tapers gradually. The breadth 

 of the front part of this section is more than double 

 as great as that of the trunk itself. AVhen the 

 animal is seen from the side (fig. 1), the greater 

 part of the ventral side of this region appears to be 

 occupied by the voluminous marsupium, the anterior 

 part of which is boldly convex, while the posterior 

 end projects only slightly in the form of a short, 

 conical prominence. At the end of this prominence 

 is seen the external opening of the marsupium, 

 bounded, as in Branchinecta, by 2 movable lips, the 

 upper of which is the larger, and ends in a pointed 

 nodule (see PI. X, fig. 12). The caudal lamellæ 

 (see PL rX, fig. 6) are comparatively short, being 

 scarcely more than double as long as they are broad 

 at the base. They exhibit a Ijroadly lanceolate shape 

 with the point narrowly rounded, and are each 

 fringed with about 19 ciliated bristles, which suc- 

 cessively increase in length towards the point. 



The eyes (PI. X, fig. 1, o) are comparatively 

 short and thick, scarcely longer than half the 

 breadth of the head, and of the usual pyriform 

 shape, with the eye-ball evenly rounded. The pig- 

 ment is dark, though with a distinct tinge of crim- 

 son in the living animal: the visual elements are 

 well-developed. The ocellus is observable as a dis- 

 tinct dark spot in the centre of the frontal part of 

 the head. 



The first pair of antennæ (figs. 1, a * and 3) are 

 comparatively' much shorter than in Branchinecta, 

 being scarcely half as long as the eyes, but in 

 other ways exhibit a very similar structure, and 

 carry at the extremity the visual olfactory papillæ 

 and sensory bristles. 



The second pair of antennæ (fig. 1, a^) are also 

 smaller than in Branchinecta, and have tlie form of 

 2 apparently ]ierfectly immovable triangular lappets 



