205 
II. 
Among the material of Thyone gibber (Sel.), collected by Dr. 
Th. Mortensen at the island of Taboga in the Gulf of Panama, 
some specimens were found, which had completely fused together 
in different ways (Fig. 4). They could not be separated without in- 
juring the skin, and on a histological examination by means of 
' sections it was found that the skin of the two specimens had com¬ 
pletely coalesced, the former limit between the two specimens hav- 
Fig. 4. Thyone gibber (Sel.). Coalesced specimens. Nat. size. 
n 
ing absolutely disappeared in the place where they touched one 
another. 
Dr. Mortensen informs me that he has observed some spec¬ 
imens apparently coalesced to have separated again when kept for 
some time in small dishes. In such cases the coalescence could 
hardly have been complete. This species is very common in some 
places at the shores of Taboga, being found under the stones, 
near high water mark. The specimens are often found attached to 
the stone so closely that they touch one another, and the pedicels of 
two specimens, when extended, must interlace between one an¬ 
other. The pedicels being very numerous this interlacing becomes 
so to say inextricable, so that they really cannot find out which 
pedicels belong to which specimen — just like the men’s legs in 
the old Danish tale of the Molbos — and ultimately first the ped¬ 
icels and then the skin itself of the two specimens fuse together. 
The coalescense, however, is only superficial. The body cavities 
of the two specimens remain separate. Neither have I found any 
