Balanoglossus

_Balanoglossus_ was described as a worm-like animal belonging to the

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Various

-- The possession of gill-slits is as interesting a feature in the organization of _Balanoglossus_ as is the presence of tracheae in

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Various

In most species of _Balanoglossus_ each gill-slit may be said to open into its own atrial chamber or gill-pouch; this in its turn opens to the exterior by a minute gill-pore.

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Various

_Amphioxus_ the reverse is the case; (b) the tongue-bar contains a large coelomic space in _Balanoglossus_, but is solid in _Amphioxus_; (c) the skeletal rods in the tongue-bars of _Balanoglossus_ are double; (d) the tongue-bar in _Balanoglossus_ does not fuse with the ventral border of the cleft, but ends freely below, thus producing a continuous U-shaped cleft.

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Various

-- The development of _Balanoglossus_ takes place according to two different schemes, known as direct and indirect, correlated with the occurrence in the group of two kinds of ova, large and small.

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Various

-- Some thirty species of _Balanoglossus_ are known, distributed among all the principal marine provinces from Greenland to New

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Various

"Memoirs on the Indirect Development of Balanoglossus," _Journ.

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Various

The vascular system does not readily lend itself to morphological comparison between such widely different animals as _Balanoglossus_ and _Amphioxus_, and the reader is therefore referred to the memoirs cited at the end of this article for further details.

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Various

The chief resemblances between _Balanoglossus_ and _Amphioxus_ in respect of the gill-slits may be stated briefly as follows: -- ([alpha]) the presence of two kinds of branchial bars in all species and also of small crossbars (synapticula) in many species; ([beta]) numerous gill-slits, from forty to more than a hundred pairs; ([gamma]) the addition of new gill-slits by fresh perforation at the posterior end of the pharynx throughout life.

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Various

One of the most singular facts concerning the geographical distribution of Enteropneusta has recently been brought to light by Benham, who found a species of _Balanoglossus_, _sensu stricto_, on the coast of New Zealand hardly distinguishable from one occurring off Japan.

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Various