BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
Bayr. Wiss. Akad., Abh. X. Pl. I. Fig. 74; Hantk., 1875, Clav. Szab. 
Sch., Pl. VI. Fig. 10; Cr. mamillegera Karr., 1865, Novara Exp., 
Geol., Th., Pl. XVI. Fig. 5; Brapy, 1884, Chall. Exp., IX. Pl. LXX. 
Figs. 17, 18; Naut. cassis F. & M., 1803, PL XVII, Fig, / etes 
Sutures smooth, segments wholly or partly beaded: Naut. calcar var. e 
F. & M., Pl. XII. Figs. a-c; Rob. calcar, tuberculata, elegans D'ORB., 1826, 
An. Sc. Nat., VII. pp. 289, 292, 293 ; Crist. erinacea KARR., 1878, For. 
Luzon, Bol. Mapa Geol. Espan., VII. p. 19, Pl. F, Fig. 3. 
Sutures and segments beaded: Crist. aculeata D'ORB., 1826, Tab. Méth., 
An. Sc. Nat., VII. p. 202; Brapy, Chall. Rep., IX. p. 555, Pl. LXXI. 
Figs. 4, 5; C. papillosa D'ORB., Ibid., p. 293; C. marginata D'ORB., Thid., 
p. 291; Rob. granulata HKN., 1875, Clav. Szab. Sch., p. 57, Pl. XIV. 
Fig. 15 ; C. echinata Bn., Chall. Rep., p. 554, Pl. LXXI. Figs. 1-3. 
II. Lineolate or costate rowelled forms. 
A. no beads or prickles: = Rob. echinata Czsz., 1847, For. Wien. Beck., I Iaid. 
Nat. Wiss., Abh. II. p. 141, Pl. XII. Figs. 24, 25; Rob. vaticana Costa, 
1855, Marna, Vatic. Mem. Nap., II. p. 122, Pl. I. Fig. 17. 
B. Segments beaded : Rob. echinata D'ORB., 1846, Bass. tert. Vienne, p. 
100, Pl. IV. Figs. 21, 22. 
At present our materials of these forms are too scantily represented to enable 
us to make up a true relationship between them, but so much could now be 
suggested that the beaded forms could possibly be included under 4 or 5 varie- 
ties, the most of them under the head of C. rotulata and cassis, the disposition 
of the beads over the surface not being taken into account as of smaller dis- 
tinguishing value. Crist. marginata D'Or». has some tendency to assume an 
oval cassis-like form, and the often emarginated keel or wing will be reduced to 
strong marginal spines. Such a form is represented in my paper on the Ret. 
Rhizop. of the Caribbean Sea, Sy. Vet. Ak. Hdl., 1882, XIX. 4, Pl. III. Figs. 
50, 51, with limbated and beaded septa, and the segments also partly beaded, 
the riper segments being more or less smooth. The semicircular anterior 
bordering of the top segment cannot be considered as a differential characteris- 
tic. The mouth is often pouting in the top of the last segment, 
The beads are often ‘small, scanty, and sometimes nearly obsolete. The dif- 
ference between C. marginata and C. aculeata Br. is more limited than at first 
sight will be observed. It attains a length of 3-5 mm. 
Caribbean Sea. 196-210 fathoms ; scarce. 
= 
S 
C. aculeata v’Orn., var. marginulinoides Gois. 
Plate V. Figs. 15, 16» 
C. aculeata D'ORB., 1826, Tab. Méth., An. Sc. Nat., VII. p. 202 (type). 
C. aculeata Br., 1884, Chall. Rep., IX. p. 555, Pl. LXXI. Figs. 4, 5. 
Guppy, 1894, For. Trinidad, Proceed. Zoöl. Soc. London, Nov. 6, 1804, Pl. XLI. Fig. 2. 
? Marg. aculeata NEUGEBOR, 1851, For. Lapugy, Siebenburg. Ver. Mittheil., II. Pl, 
IV. Fig. 21. 
