REPORT ON THE CRINOIDEA. Ii 
The nearest, and in fact the only ally of Bathycrinus is Rhizocrinus; but the 
differences between the two genera are much greater than their resemblances. The latter 
may be summarised as follows :—1. The hifascial union of the stem-joints. This is 
common to Bourgueticrinus and Mesocrinus, to the Pentacrinoid larva of Comatula, and 
the Paleozoic Platycrinus. 2. The presence of large processes on the second joints above 
the radials, which support the disk. 38. The absence of pinnules from the lower parts of 
the arms, and the union of the arm-joints in pairs, with a pinnule on the second joint of 
each pair only. 
The differences between the two types are shown in the following Scheme. 
Rhizocrinus. 
a. May have radicular cirri. 
b. Only one or two discoidal joints at the top of 
the stem, and those not very thin. 
c. Basals long; radials short, and very closely 
united. 
d. Primary interradial cords fork within the 
basals. 
e. Five arms, 
f. All the joints above the first radials are united 
in successive pairs by syzygy. 
g. The first pinnule may be either on the 
primitive sixth or eighth joint above the first 
Bathycrinus. 
a. No radicular cirri. 
b. Many thin discoidal joints at the top of the 
stem. 
c. Basals short; radials long, and comparatively 
free, 
d. Primary interradial cords fork within the 
sutures between the radials, 
e. Ten arms. 
fj. The fifth, eighth, and eleventh joints above the 
primary radials have a muscular articulation 
at each end; the remainder are united in pairs 
by trifascial articulations. 
g. The first pinnule not lower than the eleventh 
joint above the first radial. 
radial, z.e., on the epizygal of the third or 
fourth syzygial pair. 
It has been already pointed out that Bathycrinus ranges through a greater number 
of degrees of latitude than any other Stalked Crinoid, even Rhizocrinus; and it is only 
surpassed in this respect by the ubiquitous Antedon. Bathycrinus carpentert was 
found by the Norwegian North Sea Expedition as far north as 65° 55’ N. lat. ; 
while Bathycrinus aldrichianus was twice met with by the Challenger in the Southern 
Ocean beyond the parallel of 46° S. lat. In the intervening Atlantic Ocean have been 
found Bathycrinus gracilis (Bay of Biscay) and Bathycrinus campbellianus (just north 
of the equator) ; while other examples of the genus, the specific characters of which are 
as yet unknown, were dredged by the “Talisman” in the Atlantic (1883) at a depth of from 
2000 to 2380 metres (1200 fathoms).! It is distinctly an abyssal type, ranging from 
1050 to 2435 fathoms. The only Crinoids which have been found at greater depths than 
the latter are two species of Antedon. 
We have no certain knowledge of the occurrence of Bath ycrinus in the fossil state ; 
though it is by no means impossible that some of the stem-joints so common in the 
1 Rapport préliminaire sur Vexpédition du “Talisman” dans VOcéan Atlantique, Comptes rendus, t, X¢vil. 
p. 1392. 
