250 



marginale Parti hudagtige, uden tydeligt udpræget Sculptur. 

 Kjolen jevnt buet. uden Umbo. Tergalstykkerne forholdsvis 

 smaa, med Aabningsranden kortere end Basalranden. Skjol- 

 dene af sædvanlig Form, med det apicale Hjørne spidst 

 udtrukket. De ovre Sidestykker bredere end Skjoldene, 

 næsten rhombiske, med en lidet fremtrædende subcentral 

 Umbo. De midterste Basalstykker større end de øvrige, 

 bredere end lange; de dorsale ved Basis uddragne i horn- 

 tbrmige Fortsatser; de ventrale kileformigt tillobende mod 

 Midtlinien. Rostrum kort nedad frit fremspringende, hage- 

 formigt krummet; foran samme en supplementær, utuld- 

 stændigt forkalket Plade. Stilken meget stor og tyk, hen- 

 gere end Capitulum, lige. kjødagtig, cylindrisk, kun forsynet 

 med smaa og spredte Kalkkorn. Den ydre Beklædnings- 

 membran ru af fine Smaapigge. Farven brungraa. Læng- 

 den indtil 30""". 



Findesteder. Stat. 164. 200, 359. 



Bemærkninger. Den her omhandlede Form er saa 

 ulig alle de foregaaende ved Stilkens betydelige Udvikling 

 og kjodagtige Beskaffenhed samt ved Rostrums eiendom- 

 melige Form, at den allerede ved første Øiekast kjendes 

 fra samme og muligvis fortjente at opstilles som Typen fol- 

 en egen Slægt. I selve Dyrets Bygning synes imidlertid 

 ingen væsentlig Forskjel at være tilstede. 



Beskrivelse. Legemet er (se Pl. XX, Fig. 11, 12) 

 temmelig langstrakt, hvilket væsentlig skyldes Stilkens be- 

 tydelige Størrelse. Paa Spiritusexemplarer contraheres denne 

 imidlertid paa Grund af sin ringe Kalkholdighed temmelig 

 stærkt baade i Længde- og Brededimensioner, hvilket har 

 til Folge, at hele Legemets Form noget ændres. Hvad 

 Stillingen angaar i Forhold til de Gjenstande, hvortil Le- 

 gemet er fæstet. saa er den en lignende som hos Sc. aii- 

 gustvm og striolatum, idet ingen mærkbar Bøining af Stil- 

 ken forefindes. 



Capitulum er seet fra Siden (Fig. 11) forholdsvis 

 smalt og af noget uregelmæssig oval Form, bredest ved 

 Basis og noget afsmalnende mod Enden. Den ventrale Rand 

 er paa Midten noget indbugtet og Apex temmelig kort samt 

 beliggende nedenfor Skallens Axe. Valvlerne mangler nogen 

 tydeligt udpræget Sculptur og er mindre stærkt forkalkede 

 end hos de øvrige Arter, idet det marginale Parti er mere 

 eller mindre hudagtigt. Suturerne mellem dem er dog over- 

 alt tydeligt markerede. 



Kjolen er som hos de 3 foregaaende Arter ganske 

 smal og jevnt buet, uden nogen tydelig Umbo. 



Tergalstykkerne er forholdsvis smaa, men af den sæd- 

 vanlige skjævt triangulære Form og har Aabningsranden 

 betydelig kortere end Basalranden. 



Skjoldene er ikke meget mindre og sinn sædvanlig 

 uregelmæssigt firkantede, med Lateralranden længere end 

 baade Tergal- og Basalranden; deres apicale Hjørne er 

 ogsaa her uddraget i en skarp Spids, der lægger sig ud 

 over Siderne af Tergalstykkerne. 



marginal part cutaneous, without clearly prominent sculptur- 

 ing. Keel evenly arched, no umbo. Tergal segments com- 

 paratively small, with occluding margin shorter than basal. 

 Shields of usual form, with apieal corner acutely produced. 

 Upper lateral segments broader than shields, well-nigh 

 rhomboidal, with a small, salient, subcentral umbo. Median 

 basal segments larger than rest, broader than long; dorsal 

 produced at base to corniform prolations; ventral extending 

 wedge-shaped toward medial line. Rostrum short, jutting 

 out freely below, hamate; anterior to rostrum a supple- 

 mentary, in part calcareous, plate. Peduncle very large 

 and thiek. longer than capitulum. straight, carneous, cy- 

 lindric, furnished merely with small and scattered cal- 

 careous granules. The outer investing membrane rough, 

 from minute spikelets. Colour a brownish-grey. Length 

 reaching 30""". 



Loeality. — Stats. 164, 200, 359. 



Remarks. — The species treated of here differs so 

 materiaUy from all the preceding, by reason of the con- 

 siderable development and carneous character of the peduncle. 

 along with the peculiar form of the rostrum. as to admit, 

 at the first glance, of being distinguished from them, and 

 possibly to warrant its establishment as the type of a separate 

 genus. Meanwhile. in the structure of the animal no es- 

 sential deviation would appear to exist. 



Description. — The body (see Pl. XX, figs. 11. 12) 

 is rathar elongate, a character principally arising from the 

 considerable size of the peduncle. In spirit-specimens, how- 

 ever, the latter, from its limited deposit of lime. becomes a 

 good deal contraeted, both as to length and breadth, the 

 result of wbich is a slight change in the form of body. 

 As regards the position to objects whereto the body is 

 åttached, this is precisely the same as in Sr. nui/iistum 

 and Sc. striolatum, since no appreciable inflexion of the 

 peduncle can be detected. 



The capitulum. viewed from the side (hg. 11), is 

 narrow, and of a somewhat irregular-oval form, broadest 

 at the base, and slightly tapering toward the extremity. 

 The ventral margin, in the middle. is somewhat inflexed, 

 and the apex rather short. as also placed below the axis 

 of the shell. The valves do not exhibit any strictly prom- 

 inent sculpturing, and are less calcined that in the other 

 species, their marginal part being more or less eutaneous. 

 The sutures between are meanwhile everywhere distinctly 

 marked. 



The keel, as in the 3 preceding species. is quite slender 

 and evenly arched, without any distinct umbo. 



The tergal segments are comparatively small, hut of 

 the usual oblique-triangular form. and have the occluding 

 margin considerably shorter than the basal. 



The shields are not mueh smaller, and. as usual. ir- 

 regular-quadratic, with the lateral margin longer than both 

 tergal and basal; here, too. the apieal corner is produced 

 to a sharp point, that extends over the sides of the tergal 

 segments. 



