154 MAZATLAN BIVALVES 
suborbicular. The ligament has a variable number of longi- 
tudinal grooves, each broken up into portions like a necklace. 
The shell is generally suborbicular and massive (sometimes 
6 in. thick, Hanl.), and affords a safe asylum not only for 
the ordinary boring and nestling bivalves, but for numerous 
small Gasteropods, especially Coca, Odostomide, Vitrinella, 
Narice, &e., which establish themselves in empty burrows 
and in the galleries formed by numerous boring worms, in the 
coloured portion of the shell. The possession of a single valve 
therefore is quite a treasure to a patient conchologist ; as, after 
working out the borers, he will find a plentiful supply of species 
among the debris. Most of the small shells described in this 
Catalogue were thus taken from the large Chame and Spon- 
dyli, by carefully passing the shell-washings through a fine 
wire sieve, and examining the remainder under the glass. A 
single specimen of Spondylus was found to contain the follow- 
ing species :—Parapholas calva, Gastrochzena ovata and trun- 
cata, Petricola robusta, Rupellaria linguafelis, Saxicava arctica, 
Sphenia fragilis, Cumingia 3 sp., Tellina 2 sp., Veneride 5 sp., 
Gouldia Pacifica and varians, Circe margarita, Cardita Cali- 
fornica, Cardium 2 sp., Lucina, 2 sp., Kellia suborbicularis, 
Lepton 2 sp., Mytilus 2 sp., Crenella, Septifer, Lithophagus 
aristatus and plumula, Byssoarca gradata and solida, Chama, 
Tsognomon, Avicula, Anomia, Discina Cumingii, Bullide 2 sp., 
Chiton, Patella 2 sp., Siphonaria (2 varieties), Crepidula 2 sp., 
Fissurella 2 sp., Hipponyx, Vermetus 2 sp., Torimia, Trochus, 
Narica, Vitrinella 6 sp., Fossar, Littorina 2 sp., Rissoide 5 sp., 
Jeftreysia, Cerithiade 5 sp., Odostomia 6 sp., Chemnitzia 3 sp., 
Kulima 2 sp., Scalaria, Caecum 5 sp., Columbella5 sp., Nassa, 
and Marginella 2 sp: in all 103 species, of which 7 only were 
fragmentary. It is impossible to say how many more might 
have been rescued from oblivion, had not the original pur- 
chaser of the collection immediately sold off almost all the 
large shells to the keeper of a tea garden connected witha 
public house near Manchester, where they may be seen, the 
Pinne built up into grottos, and the Spondyli and large 
Patelle arranged alternately round the skirting board of liis 
“Museum.” ‘These shells were carefully washed by the publi- 
can’s servant, and the precious dirt thrown away. Mr. Hanley 
was more fortunate, and obtained many fine specimens from 
the Havre Col. The largest specimen I obtained measures 
long. 7°, lat.7°, alt.6°5. The measurement was however taken 
after the shell had been decorticated to obtain the borers. 
