7 
Det er iser paa Rygfladen, at de ere tilstede i store 
Masser. 
De store Spikler ere snart lige, snart ere de mere 
eller mindre krumbøjede og besatte med stærke Takker, 
Tab. IT, Fig. 24; ikke saa, sjeldent forgrene de sig, og 
da ere Grenene takkede, Tab. IT, Fig. 23. De have en 
noget forskjellig Størrelse, i Almindelighed indtage .de en 
Længde af 0,857”” og en Tykkelse af 0,008"  Saavel 
de store, som smaa Spikler, findes i størst Mængde paa 
Ryggen, i Fodderne, Tab. II, Fig. 14, i Tentaklerne og Ryg- 
papillerne, imedens de ere temmelig sparsomme paa Bugen. 
I Mundskivens Hud findes, foruden de smaa Spikler, 
der her ere vinklede og tæt besatte med Takker, Tab. JOE 
Fig. 20, dels rosetformige Kalklegemer, som bestaa af et 
Conglomerat af lancetdannede Kalkpapiller, Fig. 19, dels 
af Kalknet med forgrenede Udløbere, Fig. 21. Imellem 
disse Kalklegemer iagttages ogsaa et brunrødt Pigment, 
der dels er leiret i uregelmæssige Hobe, dels indesluttet i 
egne Celler. 
I Fødderne ligge Spiklerne pakkede paatvers over hver- 
andre og omgive ganske Foden, Fig. 14; det samme er 
Tilfældet med Tentaklerne og Rygpapillerne. 
Fordøielsesorganerne. 
Mundaabningen (Atriet) er stærkt muskuløs, og her 
danner Spiserørets Ringmuskler en stærk Sphincter. 
Svælget er rundt, 4”” langt, strækker sig omtr. 
2”m bagenfor Vandkarringen. Paa dets forreste Del og 
fra dets ydre Flade, der har et gulagtigt Udseende, løber 
en Mængde fine Muskeltraade, dels hen til Kalkringen, dels 
til Mundskiven. Svælget er en Fortsættelse af den ydre 
_ Hud, og har derfor vesentligen ‘den samme anatomiske 
Bygning, som denne. Men ikke alene Svælget, hele Tarm- 
kanalen har de samme Hudlag, og afvige kun forsaavidt, 
som de optræde med større eller mindre Styrke paa de for- 
skjellige Steder. 
Svelgets ydre Flade har et Peritonealovertræk, der 
flimrer; mdenfor dette iagttages et smalt hyalint Binde- ' 
vævslag, hvortil Muskellaget er bundet. Dette bestaar af 
Ring- og Længdemuskler, hvilke ere saaledes ordnede, at 
det faar et temmelig regelmæssigt gittret Udseende med 
Masker, der gaa paalangs. 
Til Muskelhudens indre Flade fæster sig et bredt, 
hyalint, kjærnerigt Bindeværvslag, hvorfra udgaa tætstaaende, 
og paa langs gaaende listeformige Fremspring. | Umiddel- 
bart indenfor dette Bindevævslag og bundet dertil, iagttages 
et Bpithellag med en tyk Cuticula. De listeformige Frem- 
on the ventral surface for instance, others crowded together 
in tufts or fasicles, fig. 11, fig. 10, fig. 22, and some 
regularly disposed in one or more spiniferous layers. It is 
more especially the dorsal surface which is densely covered 
with these spicules. : 
The large spicule are partly rectilinear, partly more 
or less incurved, and furnished with strong denticles; not 
infrequently they branch, the ramifications béing in that 
case serrate, Pl. II, fig. 23. They vary somewhat as to 
magnitude, averaging, however, in length 0.357”” and in 
thickness 0.008”". The large and the small spiculæ are 
both most numerous on the back, the suckers, Pl. II, fig. 
14, the tentacles, and the dorsal papillæ, being rather 
sparingly distributed on the belly. 
Throughout the integument investing the oral disk, 
exclusive of the spicules, which in this part of the skin 
are angular and closely denticulate, Pl. IT, fig. 20, occur 
numbers of flosculous corpuscles, a conglomerate assemblage 
of lanceolate calcareous papille, fig. 19, together with 
calcareous reticulations, from which issue ramified appen- 
dices, fig. 21. Between: these calcareous corpuscles is 
seen a brownish-red pigmentary substance, either irregularly 
distributed in patches or deposited in separate cells. 
In the ambulacral suckers, the spiculæ are transversely 
arranged, ‘one above the other, completely inyesting the 
sucker, fig. 14; a similar disposition is observed in the 
tentacles and the dorsal papille. 
Digestive Organs. 
The buceal orifice is exceedingly muscular, and at 
this point the annular muscles of the pharynx unite to 
form a powerful sphincter. ’ 
The pharynx, circular and 4” in length, protends 
about 2”” posterior to the vascular ring. On the anterior 
portion of the pharynx, .and issuing from its outer sur- 
face — of a yellowish appearance — are a number of 
delicate muscular filaments, part of which proceed to the 
calcareous ring, and part to the oral disk. The pharynx is 
a direct continuation of the outer integument, and hence 
its anatomical structure must be essentially similar. .But 
the intestinal canal, no less than the pharynx, is invested 
with the same tegumentary layers, the only difference con- 
sisting in the greater or less degree of density, or com- 
pactness, it exhibits at different points. 
Over the outer -surface of the pharynx extends a 
peritoneal membrane, furnished with vibratile cilia, within 
which is seen a narrow layer of hyaline connective tissue, 
webbed to the muscular layer. The latter consists of an- 
nular and longitudinal muscles, their mode of arrangement 
giving to the surface a somewhat chequered appearance, 
with longitudinally extending tesselle. , 
Webbed to the inner surface of the muscular membrane, 
is a broad layer of hyaline, highly nucleal connective tissue, 
from which proceed closely set, cornice-like longitudinal 
processes. Immediately beneath, and connate with, the layer 
of connective tissue, is seen an epithelial layer, furnished 
