252 
Fam. 2 . Balanidse. 
Gen. Balanus, Brug. 
82. Balanus crenatus, Brug., varietas. 
(PI. XX, Pig-. 14, 15). 
Den her afbildede Balanus afviger i det ydre saa 
paafaldende fra den for Balanerne ssedvanlige pyramidale 
eller patellalignende Form, at man mindst skulde ta?nke, 
at den lo<l sig henfore- til nogen af vore bekjendte Former. 
Og dog har en noiere Undersogelse af Skallens Valvler 
overbevist mig om, at den alene er at betragte som en 
excessiv udvildet Yarietet af den ved vore Kyster ikke ual- 
mindeligt forekommende B. crenatus Brug. Som man vil 
se, ei det vsesentlig den eiendomraelige Udvikling af de 
Kalkplader eller Valvler, der tilsammen danner Skallens 
\ .eg ( parietas), som udmmrker denne Yarietet og giver 
Ska, lien et saa i hoi Grad fremmed Udseende. Dorimod 
er do V alvler, dor begramdser Aabningen (Tergalstykkerne 
og Skjoldene) saaveliForm som Sculptur uoiagtigt af samme 
Udseende som hos den ssedvanlige Form af B. crenatus. 
Skalvseggenes abnorme Udvikling bos den her omhandlede 
Form tor inaaske forklares dewed, at Individerne fra forst 
af har vaeret staerkt sammentraengte paa et forholdsvis lidet 
Rum og under sin paafolgende Vsext saaledes har vaeret 
nodt til at skyde i Yeiret for at faa Rum. I Darwins 
Arbeide over Cirripederne er givet en Afbildning af en 
Vaiietet at den her omhandlede Art, som tydeligt naarmer 
sig til den her Fig. 15 afbildede Form, skjondt paa langt 
naer ikke visende en saadan excessiv Forlamgelse af Skal- 
vaeggen. Fig. 14 forestiller et af de mindre staerkt for- 
lsengede Individer, der imidlertig endnu maerkeligt afviger 
fra det typiske Udseende ved Skalvseggens cylindriske opad 
noget udvidede Form. 
Forekomst. Af mervserende eiendommelige Yarietet 
toges under Expeditionens sidste Togt nogle Exemplarer 
ved Hjselp af Bundskraben paa Stat. 322, X af Beeren 
Eiland, fra et Dyb af 21 Favne, haard Bund. 
Fam. 2. Balanidse. 
Gen. Balanus , Brug. 
82. Balanus crenatus, Brug., varietas. 
(PI. XX, figs. 14, 15). 
The specimen of Balanus represented in the Plate, 
exhibits so striking a deviation in its outer habitus from 
the pyramidal or patelliform aspect usually distinguishing 
the Balanidse, that few would imagine if referable to any 
oue of the previously known forms. And yet a closer ex- 
amination of the valves ol the shell, has convinced me, 
that the animal in question should be regarded as a mere 
exceptionally developed variety of B. crenatus Brug., a spe- 
cies occurring not infrequently off the Xonvegian coasts. 
As will be seen, it is chiefly the peculiar development of 
the calcareous plates, or valves, that together constitute the 
vail of the shell (parietas), which distinguish this variety, 
giving to the shell an aspect so characteristically alien. 
On the other hand, the valves that define the opening 
•(the tergal segments and the shields) have alike in form and 
in sculpture precisely the same appearance as those of the 
usual form B. crenatus. The abnormal development of 
the wall of the shell in the form treated of here, will, 
maybe, admit of explanation by assuming the individuals to 
have been originally subjected to strong compression in a 
relatively confined space, thus compelling them, during the 
progress of growth, to force an upward passage, for the 
purpose of obtaining space. In Darwin’s work on the Cir- 
ripedia, there is a drawing of a variety of the species treated 
of here, clearly approximating the form represented in fig- 
15, though far from exhibiting so remarkable a prolonga- 
tionfof the wall of the shell. Fig. 14 gives one of the 
less elongated individuals, which however still deviates 
a good deal from the typical appearance, by reason of the 
cylindric form — somewhat expanded, as it is, in an up- 
ward direction — distinguishing the wall of the shell. 
Occurrence. — Of the present peculiar variety, a 
few specimens were brought up in the dredge, on the last 
cruise of the Expedition, — at Station 322, north of 
Beeren Eiland, from a depth of 21 fathoms: hard bottom. 
