160 Records of the Indian Museum. VoL. XVIII, 
are of parasitic origin, as is shown in the following note, for which 
we have to thank Dr. Baini Prashad :— 
‘“The tubercles noted by Regan in the description of the large 
specimen of S. macmahoni are due to the encvsted glochidia of 
some Unionid. The arrangement of these parasites in this speci- 
men is rather striking. There are three to five slightly irregular 
rows on the snout and the region of the head below the eyes. On 
the anal fin there are six parallel rows following the lines of the 
fin-rays on either face. 
The number of glochidia in each row varies from about three 
to ten. In addition to those in the two situations noted by Regan 
in his account, there are a few glochidia encysted on some of the 
scales of the ventro-lateral regions of the body between the ventral 
and the anal fins. 
Owing to the glochidia being in an advanced stage of encyst- 
ment and the poor preservation of the specimen, it is not possible 
TEXxT-FIG. 2.—One of the type-specimens of Scaphiodon macmahont 
with encysted glochidia on head and fins. 
to ascertain all the larval characters. It is, however, clearly seen 
that the hinge-line is not straight but curved, and that the surface 
of the shell-valves is minutely sculptured. 
Owing to our limited knowledge of the anatomy of the 
Seistan Unionidae it is not possible to assign the glochidia to any 
definite species, but they may possibly belong to Lamellidens mar- 
ginalis subsp. rhadinaeus, Annandale and Prashad,' a form widely 
distributed in the basin of the Helmand river and recently 
described.” 
Scaphiodon macmahoni, Regan (type). 
Measurements (in millimetres), number of fin-rays, scales and pro- 
portions :— 
1. Total length (including caudal) = me 114.6 mm. 
2. Length of caudal sas fee fas 2252 2°h 5, 
3. Greatest depth of body ... .: we PISO 
4. Length of head ee wa ne 2S ae ass 
1 Rec. Ind. Mus., XVIII, pp- 59-62, pl. vill, figs. 7-11 (1919). 
