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I. The dermal diacts are hastate tornotes * / /f ...fi ' 
A. The isochelas are typically arcuate. 
1. The principal spicules are^entirely spined. 
a. The microscleres are of ^‘size range 
T^principal spicules about 5 micra thick: 
tortugasensls ( 13 )‘ 
^principal spicules about 10 micra thick: . 
macul atum { 
b. The microscleres are of two size ranges; 
lundbeckl i 
2. The principal spicules vary from shorter, entirely 
spined to longer, only partially spined: . 
oauoertas 
3. The principal spicules have extremely few, blunt 
spines: . buchanl C P )< 
B, The isochelas have peculiar long, thin, later^ alae, 
1. b.ut^ are "^herwlse commonplace: certpaS /lS^^ 
,.^ddly recurved- to form hooks: 
stylodermiam ( 
i^so 
I ^ \ 
II. The dermal diacts are oxeas: 
III. The dermal diacts are strongyles. 
A. 'The principal spicules up to 950 micra, 
60 micra: 
B. The principal spicules under 516 micra, 
der ^4 micra: 
IV. The dermal diacts are tylotes. 
clavlgerum 
microscleres to 
atlanticum c^- 
microscleres un- 
sophlum ^ , 
A. The Isochelas have peculiar, thin, sharp, lateral alae, 
1. but_.ajz£ the r wise commonplace: cert 
2. ajid/^so hav^ a peculiarly keeled central shaft: 
7 lobosum ^ 
The isochelas are typically arcuate. 
1. The principal spicules are very thick (over 20 
micra) and scarcely spined at all: , \ yy 
kymum (_ ^ — 
2. The principal spicules are entirely spined, 
a. -aafse .^bout b micra thick, the chelas about ,36 ft 
micra: lindgrenl {'^cn 
b. -g«ie /^out 15 micra thick, the chelas about 24 
micra: rooseveltl^ . 
