REVIEW OF SPENGEL’S MONOGRAPH ON BALANOGLOSSUS. 403 
There are no peripharyngeal spaces. There are four 
genital wings—a dorsal and a ventral pair—each with 
several rows of gonads,and they do not extend behind 
the gill region. The outer gill-pores are elongated to form 
slits extending between the dorsal and ventral wings. 
B. Kowalevskii, the species the development of which has 
been worked out by Bateson, adheres very closely to the 
normal type. Its chief peculiarity is the enormous length of 
the proboscis (see fig. 6). The longitudinal muscles in this 
part are arranged in regular concentric layers. The notochord 
has a rather long head. Peripharyngeal spaces are 
present, and are obviously diverticula of the trunk 
celom, their walls containing not only circular but also 
longitudinal muscles. The lateral walls of collar are 
prolonged so as to cover three or four gill-slits (the 
so-called atrial folds). The central nervous system 
has no dorsal roots, but is connected with the dorsal 
epidermis by a longitudinal ridge of cells, such as is 
found in the young Ptychodera minuta. There are 
no dorsal gonads, but there are gut-pores, though only the 
more posterior paired pores are represented. 
B. Mereschkovski is, as far as I can see, quite identical 
with B. Kowalevskii; B. sulcata has a similar proboscis, 
but its anatomy has not been investigated. 
Balanoglossus Kowalevskii is in many respects the 
central form of the whole group; from it to Glandiceps the 
transition is not difficult, to which Schizocardium is also closely 
related. Unless we suppose synapticula to have been twice 
developed we must assume that the central organs of the 
proboscis of Ptychodera have undergone reduction, since the 
synapticula have evidently arisen between Glandiceps and 
Schizocardium. 
Ontogeny. 
The chapter on Ontogeny is exceedingly disappointing. 
Professor Spengel’s observations have been confined to 
Tornariz caught with the surface-net, and his methods appear 
to have been of a very crude nature. Though he has observed 
VoL. 36, PART 3.—NEW SER. EE 
