314 THE AMERICAN NATURALIST. [Vor. XXXVI. 
The fact that Trypanosyllis is a genus of the Syllida must 
not be overlooked. Of all the annelids, this family affords 
the best and most numerous examples of asexual reproduction 
by stolonization. The small size and comparatively simple 
structure of most syllidians no doubt peculiarly adapt them to 
this mode of multiplication. On account of its great advantage 
in the dissemination of the species, this form of reproduction, 
acquired by the presumably diminutive ancestors of the two 
gigantic species of Trypanosyllis, might be retained in a grad- 
ually modified form as by slow degrees the animal became larger 
and more complex. By equally slow degrees the collateral type 
of budding would replace the linear. The development in 
both collaterally budding species of extensive intestinal diver- 
ticula (Fig. 16) in every somite from the proventriculus to the 
budding zone would obviously render inconvenient, if not 
impossible, the production of large gonads in the stock. As 
in many other syllidians the production of sexual cells would 
be more and more relegated to the most posterior somites, 
and to any linear or collateral buds that might develop in that 
region. 
The advantages of collateral over linear budding in greater 
safety and compactness, as well as the possibility of securing 
a more rapid development and a greater number of buds, 
are obvious. Species of Myrianida produce stolons with the 
greatest number of zooids, but the chain is not known to 
have over thirty zooids at any one time? This is only 60 per 
cent of the number of collateral buds present in the specimen 
of Trypanosyllis gemmipara that has been studied. The 50 
buds of the latter add practically nothing to its length, while 
the 29 buds of the example of Myrianida figured by Malaquin 
form a chain no less than 55 per cent of the entire length of 
the worm. The liability to loss or injury to which such a 
1 In 7. zebra, according to an observation recorded by Viguier in 1886 (Arch. 
de Zool. Exp., sèr. 2, tome iv, p- 364, footnote), to which the author has kindly 
drawn my attention, there occurs an apparently non-terminal stolonization which 
perhaps is a t step towards collateral budding. It is not well, however, to push 
the very far, as there is really little likeness between the two types of 
gemimation as we know them at poe 
2 See Malaquin, oc. cit., Pl. I. | 
