REPORT ON THE TUNIC AT A. 
369 
North Latitude. 
Species. 
South Latitude. 
65°-40° 
40°-30= 
30"-20° 
•20°-10= 
10=-0° 
0°-10° 
10°-20'- 
20°-30' 
30”-40° 
40°-55° 
+ 
+ 
Leptoclinum edioardsi, 
japonicum, 
jachsoni, 
ruhicundum, . 
Diplosomoides molle, . 
Diplosoma macdonaldi, 
Coeloeormus Tiuxleyi, . 
Goodsiria placenta, 
var. fusca, 
peduncnlata, 
coccinea, 
Synstyela incrustans, . 
Chorizocormus reticulatus, . 
-t- 
+ 
+ 
+ 
+ 
+ 
-1- 
+ 
+ 
+ 
•h 
_L 
9 
9 
0 
4 
7 
Total number of entries in each column. 
2 
9 
1 
25 
39 
Northern hemisphere, 29. 
Total number of entries in each hemisphere. 
Southern 
hemisphere, 76. 
This table brings out very forcibly — first, the great preponderance of Compound 
Ascidians in the southern over the northern hemisphere, there being between two and 
three times as many entries on the right liand side of the table as on the left, not- 
withstanding the fact that more than one-third of those on the latter are due to species 
obtained during the cruises of the “ Lightning ” and “ Porcupine,” which were confined 
to the northern hemisphere ; and secondly, the great abundance of Compound Ascidians 
in the far south, the two last columns in the right hand side (30°-40° and 40°-55°, 25° 
in all) containing together a good deal more than half the total number of entries. 
Consequently, it would appear from the Challenger investigations that the Compound 
Ascidians, like the Simple Ascidians, attain their greatest numerical development in 
the southern temperate zone. 
The family Botryllidse appears to be confined to the northern hemisphere, in which, 
however, it has a wide range. 
The Distomidse are well represented in both hemispheres, and they eztend widely 
both to the north and to the south of the equator. The genus Colella is mainly a 
southern form, and is only represented north of the equator by Colello, thomsoni, from 
the Philippine Islands. 
The Polyclinidse, according to the Challenger investigations, is almost entirely a 
southern family, as it is represented by about forty species in the southern hemisphere, 
(zooL. CHALL. EXP. — PAET xxxvni. — 1886.) Pp 47 
