1897.] Zoology. 157 
rangement given by Hertwig seems the best, and for that reason, if 
not for the sake of showing true genetic relationships, the synopsis 
below is given. 
A. With caudal and with one pair of lateral fins, Spadella.. 
a. Anterior teeth wanting. 
Posterior teeth many. Seizing-hooks 8-9. Length 35 mm. 
(According to Mobius). Taken off Martha’s Vineyard, North 
Atlantic, S. (Krohnia) hamata (Mob). 
b. Anterior teeth present. 
1. Seizing-hooks 6. Anterior teeth 3-5; posterior teeth 5-7. 
Length 52 mm. North Atlantic. Lat 42°, 28'; long. W.. 
50°, 55’, 30”, _ N. maxima Con. 
. Seizing-hooks 10. Anterior teeth 8; posterior teeth 18. 
A broad bilateral outgrowth of the epidermis distinguishes 
this from all others. Bahamas (Binnini), Messina, Naples, 
Madeira and Canary Islands. Length 10 mm., 
S. draco (Krohn) Langer 
B. With caudal and with two pairs of lateral fins, Sagitta. 
a. Posterior teeth wanting. Second pair of fins split posteriorly 
into 4 villus-like processes. Seizing-hooks 8. Anterior teeth 
4-6; corona ciliata forming a peculiar triangle on head and 
neck, Tail equal half total length. Bahamas (Binnini). 
Length 4 mm., S. sehizoptera Con. 
- Posterior teeth present. Fins entire. 
1. Seizing-hooks 7-8. ‘ 
a. Anterior teeth 3-4; posterior teeth 4-7. 2 external in- 
testinal diverticula. Length 24-34 mm. Martha’s Vine- 
yard, Atlantic and Pacific Oceans, S. hexaptera (Orb.).. 
b. Anterior teeth 4-5; posterior teeth 7-10. No diverticula. 
Length 5.25 mm. Jamaica, S. i tenuis Con. 
2. Seizing-hooks 8-9. 
a. Anterior teeth 4-5; posterior teeth 8-15. Caudal seg- 
ment one-third total length. Length 7-11 mm. Jamaica, 
Bahamas, N. Carolina, S. hispida Con. 
b. Anterior teeth 7-8 ; posterior teeth E a ciliata 
c ength 13-18 mm. Bahamas, 
onfined to head. Length re > 
bo 
~ 
Con.. 
4. Seizing-hooks 9-12. 
Anterior teeth 5-7 ; posterior teeth 12-15. With both ex- 
ternal and internal etedicent diverticula. Length 16-33 mm. 
Vi n English "e 
ineyard Sound, Gay head o g op a 
—F. C. KENYON. 
