38 
Guide to Crustacea. 
Table-case 
No. 5. 
This division includes, among living Crustacea, a small number 
of very peculiar forms recently discovered in the fresh waters of 
Tasmania and Victoria (Fig. 16). They are of special interest on 
account of the fact that they appear to be survivors of an ancient 
group of Crustacea of which the remains are found fossil in Car- 
boniferous and Permian rocks. The drawing of the fossil Prae- 
anaspides praecursor (Fig. 17), exhibited in the case, shows the 
great resemblance in general form between that species and the 
recent Anaspides (Fig. 16). 
Division 3. - PERACARIDA. 
The carapace, when present, does not coalesce dorsally with 
more than four of the thoracic somites. The eggs and young are 
Mysis relicta, female, from the side, c.s., “ Cervical groove ” ; m., Brood- 
pouch. (From Lankester’s “ Treatise on Zoology,” after Sars.) 
carried in a brood-pouch formed by overlapping plates attached to 
the bases of the thoracic limbs. 
The following Orders are included in this division : — 
Order 1. Mysidacea. 
,, 2. Cumacea. 
,, 3. Tanaidacea. 
,, 4. Isopoda. 
,, 5. Ajnphipoda. 
Order 1.— Mysidacea. 
The general form' is shrimp-like (Fig. 18). A carapace is 
present, but it leaves free at least five of the thoracic somites. 
